Look at the triangle show on the right. The Pythagorean Theorem states that the sum of the squares of the legs of a right triangle is equal to the square of the hypotenuse. Margaret uses this theorem to simplify and rewrite the expression (b/r)^2 + (a/r)^2 using the triangle shown. Which trigonometric identity can she prove with her expression? *

Step-by-step explanation:

Given

Required

Use the expression to prove a trigonometry identity

The given expression is not complete until it is written as:

Going by the Pythagoras theorem, we can assume the following.

So, we have:

Having said that:

The expression can be further simplified as:

Substitute values for sin and cos

becomes

- 2 + 10x³ - 21x² + 19x - 4

step-by-step explanation:

each term in the second factor is multiplied by each term in the first factor

x²(- 2x² + 4x - 1) - 3x(- 2x² + 4x - 1) + 4(- 2x² + 4x - 1) ← distribute

= - 2 + 4x³ - x² + 6x³ - 12x² + 3x -8x² + 16x - 4

collect like terms

= - 2 + 10x³ - 21x² + 19x - 4 ← in standard form

21

jk it's 20

step-by-step explanation: