Trigonometry questions involving multiple topics

Math is definitely NOT my subject & my "teacher" CAN'T teach. So some help would be amazing! Here are some example questions I want to understand:

1. How do you find the reference angles for:

-190°

-3π/4

5π/8

2. Are the following true or false & why?

cos(-175°) = cos(175°)

cos(32°) = sin(58°)

sin(π/3) = 1/sec(π/3)

cos(2π/3) = cos(4π/3)

3. Given sinθ = -3/4 and θ is in quadrant 4, find the following:

cosθ

tanθ

sin (-θ)

cos (-θ)

4. Given the function, f(x) = 2cos(x/2)+3

find the amplitude of f(x)

find the period of f(x)

find the domain of f(x)

find the range of f(x)

Please explain how you get your answers. Hopefully I'll understand them better!