trig- higher maths

Question

tan(angle = 2/5

the hypotenuse is root 29

 find cos2angle 

can someone help I am stuck on this

Answer 1

Tan θ = 2/5...draw the right triangle having leg opposite θ of length 2, and adjacent leg 5.  Therefore, indeed, the hypotenuse is √29.

 

We may say that sin θ = 2/√29, cos θ = 5√29, and then we will use the formula cos 2θ = cos²θ - sin²θ (double angle formula).

 

I let you finish this up.