# Math Help - write algebraic expression as a trig function

1. ## write algebraic expression as a trig function

square root of 7x^2-448 x= 8sec theta

2. Originally Posted by jumpman23
square root of 7x^2-448 x= 8sec theta
I don't think you have expressed the problem very clearly. Are you trying to rewrite $\sqrt{7x^2-448}$ given $x=8\sec\theta?$ In that case, substitute, and note that $\sec^2\theta-1=\tan^2\theta.$