(adsbygoogle = window.adsbygoogle || []).push({}); If tan2x=(-24/7), find the exact value(s) of sinx and cosx

Working out the answers by hand, I get

sinx = ±3/5, ±4/5

cosx = ±3/5, ±4/5

But by actually calculating x and plugging it into sinx and cosx, I get

sinx = 3/5, 4/5

cosx = 3/5, -4/5

I'm pretty sure that the latter are the answers, but how do I justify it given the ±?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Trig question

**Physics Forums | Science Articles, Homework Help, Discussion**