Question 172027: I have two questions that I am stuck on. Will you please help me.
1. Find the exact value of cot(-pi/6)
2. Find the exact value of: sin 405 degrees
I must show my work and am not sure how to do these.
Please help
Thanks
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! I have two questions that I am stuck on. Will you please help me.
1. Find the exact value of cot(-pi/6)
---------------------
The tan and cot are + - + - in quadrants I II II and IV. pi/6 is 30 degs, so -30 degs is in quadrant 4. The cot(-30) is negative, viewed as either cot(330) or -cot(30), either way.
The cot is cos/sin. The sin of 30 degs is 1/2, and the cos in sqrt(3)/2. (Can you use those, or do you need a proof?)
cot(-30) = -(sqrt(3)/2)/(1/2) = -sqrt(3)
--------------------------
2. Find the exact value of: sin 405 degrees
Trig functions are cyclic with a 360 deg cycle. You can subtract 360 from the angle any number of times, until it's less than 360. In this case, 405-360 = 45 degs
The sin(45) = sqrt(2)/2
|
|
|
