Question

Let x be an angle measure and let the real numbers a ,b ,c ,cosx be such that they make the following equation true: a cos^2(x)+bcos(x)+c = 0.
Write the equivalent quadratic equation for a, b, c, cos2x. And
Compare the given and obtained equality for a=4, b=2 and c= -1

Answer 1

Answer:

Let x be an angle measure and let the real numbers a ,b ,c ,cosx be such that they make the following equation true: a cos^2(x)+bcos(x)+c = 0.

Write the equivalent quadratic equation for a, b, c, cos2x. And

Compare the given and obtained equality for a=4, b=2 and c= -1

Answer 2

Answer:

0

Step-by-step explanation:

You need that cos 2x = 2 cos2x - 1. Some easy manipulation then gives:

a2cos22x + (2a2 + 4ac - 2b2) cos 2x + (4c2 + 4ac - 2b2 + a2) = 0.

The equations are the same for the values of a, b, c given. The angles are 2π/5 (or 8π/5) and 4π/5 (or 6π/5).