The measure of angle c will be 50 degrees. so option D is correct.
What is the angle sum property?
The angle sum property of a triangle states that the sum of the interior angles of a triangle is 180 degrees.
Consider an arc of a circle.
Suppose it subtends θ angle on the rest of the part of the circumference (at any point). Then it subtends 2θ angle on the center of that circle.
a = 90° (angle subtended in semicircle)
a + c + 40° = 180° (by angle sum postulate of a triangle)
90° + c + 40° = 180°
c + 130° = 180°
c = 180° - 130°
c = 50°
Therefore, the measure of angle c will be 50 degrees. so option D is correct.
Learn more about the triangles;
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