Question

Cos(180° – a) sin (90° – a)

Answer 1

Формулы приведения.

$\cos(180 {}^{ \circ} - \alpha ) = - \cos \alpha . \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ - - - - - - - - - - -$

$\sin(90 {}^{ \circ} - \alpha ) = \cos \alpha .$

Answer 2

To simplify the expression cos(180° - a)sin(90° - a), you can use the trigonometric identities.

1. The identity for cos(180° - a) is:

cos(180° - a) = -cos(a)

2. The identity for sin(90° - a) is:

sin(90° - a) = cos(a)

Now, substitute these identities into the expression:

cos(180° - a)sin(90° - a) = (-cos(a)) * (cos(a))

Now, multiply the two terms:

(-cos(a)) * (cos(a)) = -cos^2(a)

So, the simplified expression is:

• cos^2(a)