Question

1. Use the cosine and sine functions to express the exact coordinates of P in terms of angle θ.

Answer 1

Answer:

For a point defined bt a radius R, and an angle θ measured from the positive x-axis (like the one in the image)

The transformation to rectangular coordinates is written as:

x = R*cos(θ)

y = R*sin(θ)

Here we are in the unit circle, so we have a radius equal to 1, so R = 1.

Then the exact coordinates of the point are:

(cos(θ), sin(θ))

2) We want to mark a point Q in the unit circle sch that the tangent has a value of 0.

Remember that:

tan(x) = sin(x)/cos(x)

So if sin(x) = 0, then:

tan(x) = sin(x)/cos(x) = 0/cos(x) = 0

So tan(x) is 0 in the points such that the sine function is zero.

These values are:

sin(0°) = 0

sin(180°) = 0

Then the two possible points where the tangent is zero are the ones drawn in the image below.