First, add up his total.
79.95+2*19.99=<span>119.93
Then multiply by 1.075 (this will add the tax to the amount)
That gives us </span><span>128.92475, which we can simplify to 128.92
He had to pay $128.92
</span>

8 0

3 years ago

If tan0=-3/4 and 0 is in quadrant IV, cos20= (33/25, -17/25, 32/25, 7/25, 24/25?) and tan20= (24/7, -24/7, 7/25, -7/25, 13/7, -1

Oksana_A [137]

Answer:

cos(2θ) = 7/25
tan(2θ) = -24/7

Step-by-step explanation:

Sometimes, it is easiest to let a calculator do the work. (See below)

The magnitude of the tangent is less than 1, so the reference angle will be less than 45°. Then double the angle will be less than 90°, so will remain in the 4th quadrant, where the cosine is positive and the tangent is negative.

You can also use the identities ...

cos(2θ) = (1 -tan(θ)²)/(1 +tan(θ)²)

cos(2θ) = (1 -(-3/4)²)/(1 +(-3/4)²) = ((16-9)/16)/((16+9)/16)

cos(2θ) = 7/25

tan(2θ) = 2tan(θ)/(1 -tan(θ)²) = 2(-3/4)/((16-9/16) = (-6/4)(16/7)

tan(2θ) = -24/7

3 0

3 years ago