Question

Cos(180°+a)-sin(90°-a)

Answer 1

$Cos(180^{o}+\alpha)-Sin(90^{o}-\alpha)=-Cos\alpha-Cos\alpha=-2Cos\alpha$

Answer 2

To simplify the expression, let's use the trigonometric identities:

1. Cosine of the supplementary angle: cos(180° + a) = -cos(a)
2. Sine of the complementary angle: sin(90° - a) = cos(a)

Now, we can substitute these identities into the original expression:

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

Next, we can simplify further by combining like terms:

-2cos(a)

So, the simplified expression is -2cos(a).