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# C2 Maths help with trigonometric functions watch

1. Stuck on this question For 0<theta<2pie Solve 3cos^2 theta - 13cos theta = 3sin^2 theta - 9

I was wondering if you have to use the tan identity or just the normal one and how would you use it for this question
Many thanks
2. (Original post by washdog)
Stuck on this question For 0<theta<2pie Solve 3cos^2 theta - 13cos theta = 3sin^2 theta - 9

I was wondering if you have to use the tan identity or just the normal one and how would you use it for this question
Many thanks
Express sin^2(theta) in the form 1-cos^2(theta)

Btw its pi not pie
3. (Original post by joostan)
Express sin^2(theta) in the form 1-cos^2(theta)

Btw its pi not pie

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It's pi day today guys! Happy pi day! :P
4. (Original post by washdog)
Stuck on this question For 0<theta<2pie Solve 3cos^2 theta - 13cos theta = 3sin^2 theta - 9

I was wondering if you have to use the tan identity or just the normal one and how would you use it for this question
Many thanks
3cos^2P -13cosP=3(1-Cos^2(P))-9

6Cos^2P-13CosP+6=0

CosP=13+-5/12

CosP=8/12 OR 18/12

P=0.841068671
5. Lol thanks guys i just did this on myself after joostans help well proud ;D especially after teacher did "trigonometric functions" in 2 lessons oh well many thanks

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