Simplify:
\[
\cos(126^\circ)\cos(36^\circ) + \sin(126^\circ)\sin(36^\circ)
\]
Answer (3)
cos A cos B + sin A sin B = cos (A - B)
given expression is = cos (126 - 36 ) = cos 90 = 0
The expression cos(126°)cos(36°) + sin(126°)sin(36°) simplifies to cos(90°) according to the product-to-sum trigonometric identities. The cosine of 90 degrees equals 0, so the simplified result is 0. ;
The expression cos ( 12 6 ∘ ) cos ( 3 6 ∘ ) + sin ( 12 6 ∘ ) sin ( 3 6 ∘ ) simplifies to cos ( 9 0 ∘ ) , which equals 0 . Therefore, the final simplified result is 0 .
;
