Find all exact solutions on the interval [0, 2pi].

cos(2x) - cos(x)= 0

Using the double angle identity, rewrite the equation as

cos(2x) - cos(x) = (2 cos²(x) - 1) - cos(x)

==>   2 cos²(x) - cos(x) - 1 = 0

Factorize the left side:

(2 cos(x) + 1) (cos(x) - 1) = 0

Then

2 cos(x) + 1 = 0   or   cos(x) - 1 = 0

cos(x) = -1/2   or   cos(x) = -1

In the interval [0, 2π], we get

x = 2π/3   or   x = 4π/3   or   x = π

part 1 answer = 8

part 2 answer = 72

step-by-step explanation:

part 1 explanation = add all of the numbers, then divide by how many numbers you have. so, 200/25 = 8.

part 2 explanation = not gonna lie, this is hard to explain, so just google how to do it.

because they could drop even lower..