Question

1. What is the value of x? Show your work to justify your answer.

Answer 1

Answer:

x=72 and the exterior angle is 154

Step-by-step explanation:

We will call the unknown angle in the triangle y.  Angle y and the angle (2x +10) form a straight line so they make 180 degrees.

y + 2x+10 =180

Solve for y by subtracting 2x+10 from each side.

y + 2x+10 - (2x+10) =180 - (2x+10)

y = 180-2x-10

y = 170-2x

The three angles of a triangle add to 180 degrees

x+ y+ 82 = 180

x+ (170-2x)+82 = 180

Combine like terms

-x +252=180

Subtract 252 from each side

-x+252-252 = 180-252

-x = -72

Multiply each side by -1

-1*-x = -72*-1

x=72

The exterior angle is 2x+10.  Substitute x=72 into the equation.

2(72)+10

144+10

154