Rewrite with only sin x and cos x.
cos 3x

a. cos x - 4 cos x sin2x
b. -sin3x + 2 sin x cos x
c. -sin2x + 2 sin x cos x
d. 2 sin2x cos x - 2 sin x cos x

Option A

Solution:

Given that we have to rewrite with only sin x and cos x

Given is cos 3x

We know that,

Therefore,

 ---- eqn 1

We know that,

Substituting these values in eqn 1

 -------- eqn 2

We know that,

Applying this in above eqn 2, we get

Therefore,

Option A is correct

it would take 7/10 of an hour too fill the pool.

step-by-step explanation:

the final amount you will pay is $68.04.

the tip is determined by the pre-tax amount, so we calculate the tip based on the original bill, not after we've added sales tax.

to find the tip:

we can divide 54.00 by 100 to get 1% of 54. then we multiply that by 18.

54 / 100 = .54

.54 x 18 = 9.72

tip = 9.72$

to find the tax:

we can divide 54.00 by 100 to get 1% of 54. then we can multiply that by 8 to get 8%.

54 / 100 = .54

.54 x 8 = 4.32

tax= 4.32

now we can add the tip and tax to the bill to get our total.

54 + 9.72 + 4.32 = 68.04

total: $68.04

step-by-step explanation: