Question

simplify the expression:
cosx(cosx-secx)
should i make sec look like sin & cos first?

Answer 1

Well, secx = 1/cosx. We then have:
cosx(cosx-(1/cosx)) = cos^2x - 1 = -sin^2x, because of the trig identity that sin^2x + cos^2x = 1 :-)

Answer 2

So yes, as stated on your other question about simplifying trig equations, always break up sec, tan, cossec, cotan, etc.

Answer 3

thx ^^

Answer 4

Distribute. You will get:
\[\cos ^{2}(x) - \cos(x)\sec(x)\]
\[\cos ^{2}(x) -\frac{\cos(x) * 1}{\cos(x)}\]
\[\cos ^{2}(x) - 1\]
\[-\sin ^{2}(x)\]

Answer 5

thx again ^^

Answer 6

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