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# Identities question help watch

1. Spoiler:
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Every time i make a thread i always end up being able to work them out haha
2. For the first question, what are the two values you have?

For the second, can you make the equation into a quadratic in cos(x)?
3. (Original post by eatingkiwi)
Solve 2sin^2x = 5cosx + 4 between 0 and 360 degrees.

Please could somebody explain what to do?
three
4. For the first one you should have gotten a quadratic with 2 roots. That will give you 4 answers by the end.

For the second one you want
5. Solve 2sin^2x = 5cosx + 4 between 0 and 360 degrees. I have no idea how to go about this one.
sin^2x+cos^2x=1

2(1-cos^2x) = 5cosx + 4
if X=cosx
then -2X^2-5X-2=0
delta=25-4*-2*-2=3^2
then X1=... and X2=... then x=....
6. (Original post by dguess499)
Solve 2sin^2x = 5cosx + 4 between 0 and 360 degrees. I have no idea how to go about this one.
sin^2x+cos^2x=1

2(1-cos^2x) = 5cosx + 4
if X=cosx
then -2X^2-5X-2=0
delta=25-4*-2*-2=3^2
then X1=... and X2=... then x=....
Can you solve the quadratic -2X^2 - 5X -2 = 0?

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