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deedee

SOME IMP FORMULAES IN TRIGO......AT A GLANCE..

1.sin(A+B)=sinAcosB+cosAsinB

2.sin(A-B)=sinAcosB - cosAsinB

3.cos(A+B)=cosAcosB- sinAsinB

4.cos(A-B)=cosAcosB+sinAsinB

5.tan(A+B)=(tanA+tanB)/1- tanA*tanB

6.tan(A-B)=(tanA-tanB)/1+tanA*tanB

7.cot(A+B)=(cotAcotb-1)/(cotB+cotA)

8.cot(A-B)=(cotAcotB+1)/(cotB-cotA)

1.sin(A+B)* sin(A-B)=sin^2A - sin^2B

=cos^2B - cos^2A

2.cos(A+B)* cos(A-B)=cos^2A -sin^2B

=cos^2B -sin^2A

1.sin2A= 2sinAcosA=2tanA/1+tan^2A

2.cos2A=cos^2A-sin^2A=(1-tan^2A)/(1+tan^2A)

3.tan2A=2tanA/1-tan^2A

4.cot2A=(cot^2A-1)/2cotA

5.sin3A=3sinA-4sin^3A

6.cos3A=4cos^3A- cosA

7.tan3A=(3tanA-tan^3A)/(1- 3tan^2A)

if A+B+C=180 degrees

then..................

1.sinA+sinB+sinC=4cosA/2*cosB/2*cosC/2

2.sin2A+sin2B+sin2C=4 sinA*sinB*sinC

3.cos2A+cos2B+cos2C=-1-4 cosA*cosB*cosC

4.tan2A+tan2//b+tan2C=tan2A*tan2B*tan2C

5.tan3A+tan2B+tanC=tan3A*tan2B*tanC

..........do comment..............i knw it's elementary ....& u'll r damn experts in it ............BUT........it's confusing sometimes so it's imp. 2 hav them all 2gether............

so dat we keep them in mind by comparing them..........

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