Use the relationship between supplementary angles ∠a and ∠b. What is m∠a if m∠b=121°?(1 point)
Responses
A. 59°
59 degrees
B. 301°
301 degrees
C. 31°
31 degrees
D. 121°
Since ∠a and ∠b are supplementary angles, their measures add up to 180 degrees.
m∠a + m∠b = 180°
Since m∠b = 121°, we can substitute this value into the equation:
m∠a + 121° = 180°
To find m∠a, we can isolate it by subtracting 121° from both sides of the equation:
m∠a = 180° - 121°
m∠a = 59°
Therefore, the answer is A. 59°.