Question

Find the exact value of the trigonometric function. Do not use a calculator.
cot⁡(-5π/4)

A. -1
B. -√2
C. 1
D. -√2/2

Answer 1

I started by converting radians to degrees.
-5pi/4 = (-5(180))/4

Answer 2

Then what? :) @Littlebird

Answer 3

It's in my picture

After that first step, I had -225 degrees.
I went clockwise -225 degrees around my pretend graph until I got to a 45 degree angle in the upper left quadrant. This line allowed me to make an imaginary 45-45-90 triangle. The side lengths of this type of triangle are a, a, and asqrt(2). My sign chart/pretend graph has a window of (-1,1). The one side of the triangle would equal -1. The side adjacent to it would be positive 1, however, because it is above the x axis. The hypotenuse would equal sqrt(2). Cot is the opposite of tangent. Using SOHCAHTOA I figured Cot=adjacent/opposite. This gave me my answer of -1.

Answer 4

I double checked with a calculator and still got -1.

Answer 5

Thank you so much!