A level Maths Proofs Question Help

Question is:
P = 3costheta
Q = 2sintheta
aP^2 + bQ^2 = c where a,b and c are integers

From that I take it that:

$9a\cos^2\theta+4b\sin^2\theta=c$

What do you mean by prove it's true? It's clearly not true for all a,b,c.

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Can you check the wording of the original question?

No its true

No its true I asked my teacher today and she solved it the wording of the question is right

costheta = p/3
sintheta = q/2
Use the trig identity cos^2 + sin... = 1
4P^2 + 9Q^2 = 36

You did the same thing as me subbing in P and Q directly haha so I don’t blame you

Doesn't hold for $P=1, Q=2$ so it's not true for all $P,Q$ in the integers - the wording of the question IS off.

The wording of the question never said all integers.., why would you assume that?