Question

2sin²A - cos²A =1 . Find the value of A

Answer 1

2sin²A - cos²A=1,

2(1-cos²A) - cos²A=1,

2-2cos²A - cos²A =1,

2-3cos²A=1,

then

2-1=3cos²A,

3cos²A=1,

cos²A=1/3,

cosA=1/√3,

then

A=cos^(-1)[1/√3]