Which equation correctly uses the value of x to represent the cosine of angle a?

the sum of all the angles in a triangle are equal to 180

so you can add   the 3 given angles together to equal 180:

5y + 2y + 2y = 180

or since all three angles have the same letter, combine the 3 angles to equal 180:

9y = 180

d. it is a convex pentagon because it has five sides and none of the sides would extend into the inside of the polygon.

step-by-step explanation:

answer: this is not a question

step-by-step explanation: this is a answer

a

step-by-step explanation:

strong negative correlation