Question

If sin theta + sin2 theta + sin3 theta = sin alpha and cos theta + cos2 theta + cos3 theta = cos alpha , then theta is equal to
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Answer 1

Answer : 2A

Step-by-step explanation:

SinA+sin3A+sin2A=sinB

2sin(A+3A)/2*cos(3A-A)/2+sin2A=sinB

2sin2A*cosA+sin2A=sinB-----(1) Similarly in case of cos

2cos2A*cosA+cos2A=cosB------(2) Dividing 1&2

Sin2A(cosA+1)/cos2A(cosA+1)=sinB/cosB

tan2A=tan B

​2A=B