Double angle identity for cosine:

By the Pythagorean theorem, if

, it follows that

:

where we take the positive root because

, and

is non-negative throughout this domain.
So we have
Answer:
the anwser is 66,875
Step-by-step explanation:
Answer:
it is the 2nd 1
Step-by-step explanation:
i know this because i do
Answer:
Option A, 80π
Step-by-step explanation:
4²×5π
= 80π
Answer:
You will have 40 mins before 100%
Step-by-step explanation: