The measure of angle 'a' is 48°.
We need to find the measure of 'a'.
What is the circle theorem of diameter?
Angles are formed by drawing lines from the ends of the diameter of a circle to its circumference from a right angle.
There is a diameter of the circle through point O. The bottom right angle is inscribed and that intersects a diameter, so its measure is 90°.
Now, a + 90°+ 42° = 180°
⇒a + 132°= 180°
⇒a = 48°
Therefore, the measure of angle 'a' is 48°.
To learn more about the circle's theorem visit:
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