IIT JEE , AIEEE Forum - Mathematics , Trignometry - trigo [admin]: question to find range of theta

kirtana

hii
here's a question,

cos(sin

) = 1/

2

find the range of

edison

Dear Kirtana,

could you please verify your problem!!!

I expect one of the function sin or cos to be inverse.

kirtana

i know(i thought so myself), but i verified, its right...there's even a solution to it.. i'll post it as soon as i can......

puneet1622

Well there will not be range but exact values for

... the reasons are clear ... cos(sin

) = 1/

2 will have exact solutions which are

/4 , -

/4, 2

+

/4 , 2

-

/4 and so on ...

Now the sin

can lie between - 1 ad 1 only ... and thus only feasible solutions are

/4 and -

/4 .

Now the equation reduces to sin

=

/4

and sin

= -

/4

The solution to these equations will give value of the

.

I hope this helps

cheers ..!!!!!!

puneet

This answer seems to be perfecto !!! Gr8 work done !!

kirtana

hiii

thanx for the answer, but i wud like to show what i solved.. cud u plz tell me whether my answer is right........

for 0 <

<

/2

sin

for all

now for any 2 angles

and

if

<

cos

> cos

using this ,

cos

cos ( sin

)

so,

cos

1/

2

cos

/4

hence,

/4

hence'

/2

/4

do you think it's wrong??

plz tell me..

puneet

Well yes this is correct !!

If u want to find the range then this is also fine ... all depends on what the question demands !!

vaibhav1729

hey plz prefer a good book 4 trigonometry ,properties of triangles demoivers etc

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