Question

Find all solutions on the interval [0.2pi)
A) -3sin(t)=15cos(t)sin(t)

I have no clue...

b) 8cos^2(t)=3-2cos(t)

All i did was move around the equation to make an quadratic for B.
so
-8cos^2(t)-2cos(t)+3 = 0

Answer 1

what, forgotten your algebra I, now that you're taking trig?

-3sin(t)=15cos(t)sin(t)
15cos(t)sin(t) + 3sin(t) = 0
3sin(t)(5cos(t)+1) = 0
sin(t) = 0
or
cos(t) = -1/5
So, find the 4 values of t which do that.

8cos^2(t)=3-2cos(t)
8cos^2(t)+2cos(t)-3 = 0
(4cos(t)+3)(2cos(t)-1) = 0
cos(t) = -3/4 or 1/2
now go for it.