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Catalogs Discussion Forums -> Algebra -> If z=m-ni/1-l and l^2+m^2+n^2=1, then show that 1-iz/1+iz= -(l+mi/n+1) "i" is iota -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
1 replies   

    let z = x + iy


          z = (m-in)/(1-l) =  x + iy 


or      x + iy  = ( m / (1-l)) + ( - in / (1-l) )


        compare both side--


or     x = m / ( 1-l )     and   y  = n / ( l -1)


L.H.S-   ( 1-iz /1+iz ) = ( 1 - (x + iy  ) ) / ( 1 + (x + iy  ) ) 


    or


      -----------------------Eq.(1)


put the value x and y -- partially solve numerator and denomenator


part(1)-


   


   put the value (  m2+n2=1 - l2  )


  


  


part-(2)





 


put the value of part(1) and part(2) in Eq.(1)---


 



prove this.......


 

Catalogs Discussion Forums -> Trignometry -> PLEASE SOLVE MY QUESTIONS -> Go to message
This Post 5 points    (Olaaa!! Perrrfect answer.   in 1 votes )   [?]
8 replies   

well try  vnkt.swaroop ,


Dear REJAULMA,


I think a,b,c are the sides of triangle and Let A,B,C are the respective angles which are in AP


so 2B =A+C            and since A+B+C =180


hence 2B = 180-B


hence B=60


now apply Sin Rule:


SinB/b =Sin C/c


or Sin60 /b = Sin C/c


or sinC = c Sin60 /b


or sin2 C = c2 Sin260 /b2  =3c /4b2


from given eq:  sin2 C = 2b2/4b2


or sin2 C = 1/2   or Sin C =1 / root(2)    =>   C =45


hence ,A = 75


 

Catalogs Discussion Forums -> Integral Calculus -> integerate quickly -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
4 replies   

good work sboosy


well done


 

Catalogs Discussion Forums -> Analytical Geometry -> A(-a,0); B(a,0) are fixed points. C is a point which divides AB in a constant ratio tan . -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
1 replies   

Dear,


Let P be (x,y).


in triangle APC , LET <APC = A  and < PCA = B


 hence ,<BPC = A    and <PCB = (180-B)


Apply sin  Rule  in both triangles:


(Sin A / AC ) = (Sin B/ AP)  ..................eq(1)


and (Sin A / CB ) = (Sin B/ PB).................eq(2)


from (1) and (2) , equate Sin A/Sin B:


(AC / AP) = (CB / PB)


or (AC / CB) = (AP / PB)


or tan = (AP / PB)                             since (AC/CB) = tan


or PB tan = AP


or PB2 tan2 = AP2


or [(x-a)2+y2 ] tan2 = [(x+a)2+y2 ]


or x2(tan2 -1)+y2 (tan2 -1) + a2 (tan2 -1) - 2ax (tan2 +1)=0


or x2+y2+a2 - 2ax (tan2 +1)/(tan2 -1)=0  


or x2+y2+a2 + 2ax (tan2 +1)/(1-tan2)=0  


or x2+y2+a2 + 2ax (Sin2 +Cos2)/(Cos2-Sin2)=0   


or x2+y2+a2 + 2ax (1)/(Cos2)=0  


or x2+y2+a2 + 2ax Sec2=0


please check your question it may be sec instead of cosec.


 


 


 

Catalogs Discussion Forums -> Analytical Geometry -> x,y axis are perpendicular ,then why thier multiplication of slope is not equal to -1???? -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
3 replies   

Dear


 the condition is valid only when the slopes have some defined  values.


but in this case since slope of y axis is undefined so the condition is not valid for this case and all other cases where the lines are parellel  to  y axis e.g. x=2 or so on........


so flaringstorm is right.


 


 


 


 

Catalogs Discussion Forums -> Trignometry -> Prove -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
4 replies   

good work  sachinguptaiit


 


 

Catalogs Discussion Forums -> Integral Calculus -> integrate sec(3x)sec(5x)sec(8x) -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
1 replies   

let I =sec(3x)sec(5x)sec(8x)


       = 1/(cos(3x)cos(5x)cos(8x)) =  ( A/cos(3x)) + ( B/cos(5x)) + ( C/cos(8x))  ----------Eq.(Q)


   ==>>>    1 = Acos(5x)cos(8x) + Bcos(3x)cos(8x) +  Ccos(3x)cos(5x)         ----------------- Eq.(1)


             in Eq.(1)


         component of A and B will be zero bcoz cos(pie by 2)= 0;


  then    


                


                  in Eq.(1)


              component of A and C will be zero bcoz cos(pie by 2)= 0;


           


         


         


          in Eq.(1)


         component of B and C will be zero bcoz cos(pie by 2)= 0;


        


        


      


        PUT THE VALUE  A,B  AND  C in eq.(Q)  


      


       Integrate..... 


 


      


                    


        


put the value


 


       


    

Catalogs Discussion Forums -> Trignometry -> In tri. ABC base=6 &area=12 tha differ. of base angles is 60 degree,p.t. 8sinA-6cosA=3 -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
1 replies   

let base a=6, differ. of base angles B-C=600,  AREA=12


                   A+B+C=1800


                    B+C=1800 - A


               TAKEN Cos both side---


                  Cos(B+C)=Cos(1800 + A )


                  Cos(B)Cos(C) - Sin(B)Sin(C) = - Cos(A)  ---------------------  Eq.(1)


                  B - C =600


                TAKEN Cos both side---


               Cos(B - C)=Cos(600)


               Cos(B)Cos(C) + Sin(B)Sin(C) = 1/2 ----------------------------Eq.(2)


                Eq.(2) - Eq(1)


               2Sin(B)Sin(C) = Cos(A) + (1/2)  ----------------------Eq.(3)


               As we know that--


             


            


          


            put the value SinB and SinC in Eq.(3)


           


           


           


           


          


         


         


          


          Hence Prove.....


          

Catalogs Discussion Forums -> Algebra -> Determinant -> Go to message
This Post 2 points    (Olaaa!! Perrrfect answer.   in 1 votes )   [?]
1 replies   

=


Applying R1-->aR1 , R2-->bR2 and R3-->cR3



 


      


 


Applying C3--> C1 + C3


 



 


taking (ab+ac+bc) common


 






Applying C3--> C3 - C2


 



 



 


 

Catalogs Discussion Forums -> Differential Calculus -> integrate dx/Tanx+Cotx+Secx+Cosecx -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
2 replies   

let A = Tanx+Cotx+Secx+Cosecx


     A = (Sinx/Cosx)+(Cosx/Sinx)+(1/Cosx)+(1/Sinx)


        = (Sinx^2+Cosx^2+Sinx+Cosx)/Sinx.Cosx


        = (1 + Sinx+Cosx)/Sinx.Cosx


 multiply by (Sinx+Cosx-1) in denominator and numerator..     


     A  = (Sinx+Cosx+1)(Sinx+Cosx-1) / (Sinx.Cosx)(Sinx+Cosx-1)


          = (Sinx^2+Cosx^2+2Sinx.Cosx-1) / (Sinx.Cosx)(Sinx+Cosx-1)


          = (1+2Sinx.Cosx-1) / (Sinx.Cosx)(Sinx+Cosx-1)     


          = (2Sinx.Cosx) / (Sinx.Cosx)(Sinx+Cosx-1)    


          = 2 / (Sinx+Cosx-1)  


    I     = integrate dx/(Tanx+Cotx+Secx+Cosecx)


    I    = integrate dx/A


    I    = integrate (Sinx+Cosx-1) dx/2


    I   =  (-Cosx + Sinx -x)/2


 


 

Catalogs Discussion Forums -> Algebra -> AP for nCr -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
5 replies   
good work b_srikalyan009
Catalogs Discussion Forums -> Integral Calculus -> integerate the following please 1/cosx-sinx .dx (dont use the partial fraction) -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
4 replies   
good work asmit.

Dear swashata4iit,

it will be pie/4 not pie/2, rest approach is fine

Catalogs Discussion Forums -> Algebra -> quadratic help -> Go to message
This Post 5 points    (Olaaa!! Perrrfect answer.   in 1 votes )   [?]
2 replies   
Dear,

Let f(x) = ax2+bx+c

f(x) > 0 for x in R , hence a>0 and (b2-4ac)<0

f'(x) = 2ax+b

and f''(x) = 2a

then g(x) = ax2+bx+c + 2ax+b+2a

or g(x) = ax2+(b+2a)x+(c+b+2a)

now g(x) is a quadratic , and since a>0 then we have to prove that :

D = (b+2a)2-4a(c+b+2a)<0

or D =  (b2+4a2+4ab)-(4ac+4ab+8a2)

or D =(b2-4ac)-4a2

since (b2-4ac) <0

so D<0

hence g(x) >0 for x in R

Catalogs Discussion Forums -> Trignometry -> TRigonomerical eq. -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
2 replies   
good work sankydreams

Catalogs Discussion Forums -> Differential Calculus -> calculus -> Go to message
This Post 0 points    (Olaaa!! Perrrfect answer.   in 0 votes )   [?]
1 replies   
2003f'(x)+2004f(x) >=  2004
 
hence f'(x) >= (2004/2003)*(1-f(x))
 
now case 1)  1-f(x) > 0 or f(x) <1
 
f'(x)/ [1-f(x)} >= (2004/2003)
 
 
integrate on both sides:
 
you will get :
 
-ln[1-f(x)] > = (2004/2003)x
 
or ln[1-f(x)] < = (2004/2003)x
 
or f(x) > =1+ e^ (2004/2003)x
 
hence f(x) >1 which is not possible as we take f(x) < 1
 
so no such f(x) possible in this case
 
case (2) f(x) > 1  or [1 - f(x)] < 0
 
  
f'(x)/ [1-f(x)] <= (2004/2003)
 
 
integrate on both sides:
 
you will get :
 
-ln[1-f(x)] < = (2004/2003)x
 
or ln[1-f(x)] > = (2004/2003)x
 
or f(x) < =1+ e^ (2004/2003)x
 
hence f(x) <1 which is not possible as we take f(x) > 1
 
so no such f(x) possible in this case
 
so only function  possible is : f(x) =1
 
 
 
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