[djcartel]

Here we go, Find sin2a, cos2a, and tan2a given tan(theta)= -24/7. OK, I know sin2a=2sin a cos a and tan x=sin x/cos x, and tan also =y/x. Knowing that the first thing I did was r=sqrt of -24^2+7^2 which =625. 625 is going to be my denominators for sin2a and cos2a. If possible can someone show me a step by step way of doing this so I may apply those steps with the rest of my homework??

[s_cianci]

You've found r, so now you can determine sin(theta) and cos(theta). Now just plug these values into the formulas. You know sin 2a = 2*sin a*cos a. Also, cos 2a = cos^2 a - sin^2 a. Lastly, tan 2a = (sin 2a)/(cos 2a).