Equivalent Expression for cot(-π/4) in Terms of Acute Angle

[Veronica_Oles]

Homework Statement

State an equivalent expression in terms of the related acute angle?
(A) cot(-π/4)

Homework Equations

The Attempt at a Solution

(A) I made the the unit circle and since its negative I went clockwise and made it into the fourth quadrant. I ended up getting -cotπ/4. However the answer is not the one that the textbook has given. I am a little confused.
The textbook has given the answer cot3π/4, but I thought we were supposed to go clockwise because it is negative?

 

[PeroK]

Homework Statement

State an equivalent expression in terms of the related acute angle?
(A) cot(-π/4)

Homework Equations

The Attempt at a Solution

(A) I made the the unit circle and since its negative I went clockwise and made it into the fourth quadrant. I ended up getting -cotπ/4. However the answer is not the one that the textbook has given. I am a little confused.
The textbook has given the answer cot3π/4, but I thought we were supposed to go clockwise because it is negative?

An acute angle is one that is less than $\pi /2$. I've never seen this used for negative angles, so I'm not sure whether $-\pi /4$ would be considered acute. In any case, $3\pi /4$ is not an acute angle. It's actually a "reflex" angle (I had to look that one up).

I thought your answer was correct. $\pi /4$ is definitely an acute angle.

 

[Mark44]

I agree with @PeroK -- $3\pi/4$ is not an acute angle.

It's actually a "relflex" angle (I had to look that one up).

I'll bet what you actually looked up was "reflex".

 

[Veronica_Oles]

An acute angle is one that is less than $\pi /2$. I've never seen this used for negative angles, so I'm not sure whether $-\pi /4$ would be considered acute. In any case, $3\pi /4$ is not an acute angle. It's actually a "reflex" angle (I had to look that one up).

I thought your answer was correct. $\pi /4$ is definitely an acute angle.

I just asked my teacher, I got the angle correct. Thx.