- #1
LiHJ
- 43
- 2
Homework Statement
Dear Mentors,
I have some doubts on this question that I was doing from my textbook.
Question:
Given that tan A =(-2), find the exact value of sin(-A)
My doubts are:
For angle A to be negative, angle A should be on the 2nd or 4th quadrant. But than I will have 2 possible answers. However the textbook only give 1 answer.
So I further analyze again. If the question didn't specify on how angle A is like should we stick to the principle value. Since principle value of tan is from -90 degree to 90 degree. Than angle A should be at the 4th quadrant only. So sin(-A)= - sin(A), sin A = -(-2/√5)= 2/(√5) which is the answer as given.
Can any Mentors please advise me on this. Whether I'm thinking correctly.
Thank you so much.