Question

What is the relationship among mL BCD, M L A, and m L B in the figure below?

B
75
40°
A.
40 ° + 75° = 180° - m 2 BCD
В.
40° + 75° = m 2 BCD
C 40° - 75º = m 2 BCD
D
40° - 75°+ m BCD = 180°

Answer 1

75"

Explanation:

Answer 2

The relationship between the given angles is:

40° + 75° = m∠BCD

How to find the angle relationship?

The exterior angle of a given triangle equals the sum of the opposite interior angles of that triangle. If an equivalent angle is taken at each vertex of the triangle, the exterior angles add to 360° in all the cases.

Now, the two opposite interior angles here are:

m∠A and m∠B

The exterior angle is m∠BCD

Thus:

m∠A + m∠B = m∠BCD

Thus:

40° + 75° = m∠BCD