Prove that sin alpha * sin (90 - alpha) - cos (90-alpha) * cos alpha

Question

Carsen Bartlett

Mathematics

28 February, 16:44

Prove that sin alpha * sin (90 - alpha) - cos (90-alpha) * cos alpha

+2

Answers (1)

Know the Answer?

Morgan Rivera · Answer 1

It is equal to 0.

Step-by-step explanation:

I can simplify it as follows:

sinα sin (90 - α) - cos (90 - α) (cosα)

Now sin (90 - α) = cosα and cos (90 - α) = sinα) (for α < 90)

So the expression becomes:

sinαcosα - sinαcosα

= 0.