Question

Please help will give brainiest!!!

Answer 1

Answer:
b. $\frac{ \pi }{4} or \frac{5 \pi }{4}$

Explanation:
Before we begin, remember that:
tan α = $\frac{sin \alpha }{cos \alpha }$ 

Now for the given, we have:
cos θ - tan θ * cos θ = 0
cos θ - $\frac{sin theta }{cos theta }$ * cos θ = 0
cos θ - sin θ = 0
cos θ = sin θ
Now, divide both sides by cos θ, we get:
1 = tan θ

Following the ASTC rule, we know that the tan function is positive in the first and third quadrants.
This means that:
either θ = $\frac{ \pi }{4}$

or θ = π + $\frac{ \pi }{4}$ = $\frac{ 5 \pi }{4}$

Hope this helps :)

Answer 2

Answer is: b) 
How: Re-arrange formulae knowing tan(theta) = sin(theta)/cos(theta)
such that it become: cos(theta) -sin(theta)/cos(theta) x cos(theta) = 0.
From there; cos (theta) = sin(theta) (by re-arranging). Now, substitute figures of b), pie/4 = 45 degrees. At 45 degrees, sin(45) = cos(45) = 1/square root of 2. Also, 5pie/4 = 235 degrees. At 235 degrees, sin(235) = cos(235) = -1/square root of 2