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# C3 Trig Urgent Help Needed! watch

1. Dear All,
I have already sweated over this question for an hour and its starting to get on my nerves. I was hoping if the brightest minds on TSR would mind giving me a helping hand.
Solve in the interval

Thanks,
Saran
2. change the cot into cosec and form a quadratic, bam!

2cot^2=2(cosec^2-1)
3. 1+Cot^2theta=cosec^2theta
4. (Original post by Diaz)
1+Cot^2theta=sec^2theta
Aint it cosec?
5. (Original post by Diaz)
1+Cot^2theta=sec^2theta
It's cosecant:

6. (Original post by Wesssty)
Aint it cosec?
What happens when you do it in your head
Edited
7. (Original post by saran35)
Dear All,
I have already sweated over this question for an hour and its starting to get on my nerves. I was hoping if the brightest minds on TSR would mind giving me a helping hand.

Thanks,
Saran
cot^2(theta) = cosec^2(theta) - 1

so 2cosec^2theta - 2 = 7cosec theta - 8
assume cosec theta = y
2y^2 - 2 =7y-8
2y^2 -7y + 6 = 0
(2y-3)(y-2) = 0
y = 3/2 or 2
so 1/sin^2(theta) = 3/2 or 2

sin^2(theta) = 2/3 or 1/2
then square root everything and solve normally.

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