Question

IF SINA + 2COSA = 1
THEN PROVE
2SINA - COS A = 2

Answer 1

Hello dear,
sin(A) = 1 - 2*cos(A)

Squaring both sides:

sin²(A) = 1 - 4*cos(A) + 4*cos²(A)

1 - cos²(A) = 1- 4*cos(A) + 4*cos²(A)

5*cos²(A) - 4*cos(A) = 0

cos(A)*(5*cos(A) - 4) = 0

cos(A) = 0 and cos(A) = 4/5

When cos(A) = 0, sin(A) = 1

2*sin(A) - cos(A) = 2(1) - 0 = 2
I hope you understand dear:-)