Question

(a) If cos² (34°) - sin² (34°) = cos(A°),then
A =
degree’s

Answer 1

`~~~~~~~\cos^2 \left(34^(\circ)\right) - \sin^2 \left( 34^(\circ) \right)=\cos A\\\\\implies \cos \left( 2 \cdot 34^(\circ) \right) = \cos A~~~~~~~~~~~~~;[\cos 2x = \cos^2 x -\sin^2 x]\\\\\implies \cos \left(68^(\circ)\right) = \cos A\\\\\implies A = 68^(\circ)`