cosx = 2tanx Find the numberical value of cos^2x.
K Kushballo7 New member Joined Oct 20, 2005 Messages 17 Nov 6, 2005 #1 cosx = 2tanx Find the numberical value of cos^2x.
U Unco Senior Member Joined Jul 21, 2005 Messages 1,134 Nov 6, 2005 #2 G'day, One way: Rewrite 2tanx as \(\displaystyle \frac{2\sin{x}}{\cos{x}}\) Multiply through by cosx. Rewrite \(\displaystyle \cos^2{x}\) as \(\displaystyle 1 - \sin^2{x}\). Solve the quadratic -you may find it easier to let sinx = t, and solve for t using the quadratic formula, then relate back to x. Then get (cosx)^2 from there.
G'day, One way: Rewrite 2tanx as \(\displaystyle \frac{2\sin{x}}{\cos{x}}\) Multiply through by cosx. Rewrite \(\displaystyle \cos^2{x}\) as \(\displaystyle 1 - \sin^2{x}\). Solve the quadratic -you may find it easier to let sinx = t, and solve for t using the quadratic formula, then relate back to x. Then get (cosx)^2 from there.
