Learn how to solve problems step by step online. Solve the trigonometric equation 15cos(x)^2-17cos(x)+4=0. We can try to factor the expression 15\cos\left(x\right)^2-17\cos\left(x\right)+4 by applying the following substitution. Substituting in the polynomial, the expression results in. Factor the trinomial 15u^2-17u+4 of the form ax^2+bx+c, first, make the product of 15 and 4. Now, find two numbers that multiplied give us 60 and add up to -17.

Solve the trigonometric equation 15cos(x)^2-17cos(x)+4=0