SOLUTION: help please. Solve: 2sin^2(theta) - 5sin(theta) +3 = 0 on [0,2pi] I am not sure on this as I get -1 and -3/2 Thanks for any help.

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: help please. Solve: 2sin^2(theta) - 5sin(theta) +3 = 0 on [0,2pi] I am not sure on this as I get -1 and -3/2 Thanks for any help.       Log On


   

Question 1090232: help please.
Solve:
2sin^2(theta) - 5sin(theta) +3 = 0 on [0,2pi]
I am not sure on this as I get -1 and -3/2
Thanks for any help.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Close, but your signs are off and you need to back-substitute.
u=sin%28theta%29
Then,
2u%5E2-5u%2B3=0
%28u-1%29%282u-3%29=0
So,
u-1=0
u=1
and
2u-3=0
2u=3
u=3%2F2
Now back-substitute,
sin%28theta%29=1
theta=pi%2F2
and
sin%28theta%29=3%2F2
No theta solution since abs%28sin%28theta%29%29%3C=1
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highlight_green%28theta=pi%2F2%29
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