Enter your answer and show all the steps that you use to solve this problem in the space provided.
A line segment ACD is shown with triangle ABC drawn so that AC is the base of the triangle. Angle BAC is labeled with 72 degree sign, and angle BCD is labeled with 113 degree sign.
Write a list of steps that are needed to find the measure of
∠
B
.
ACD is not a line segment
1. Draw a line from point B to point D to create a straight line.
2. Label the angle created by the line BD as ∠B.
3. Use the angle sum theorem to calculate the measure of ∠B.
4. Angle sum theorem states that the sum of the measures of the angles of a triangle is 180°.
5. Therefore, ∠BAC + ∠BCD + ∠B = 180°
6. Substitute the given values for ∠BAC and ∠BCD: 72° + 113° + ∠B = 180°
7. Solve for ∠B: ∠B = 180° - (72° + 113°)
8. ∠B = 180° - 185°
9. ∠B = -5°