Answer :
Answer:
m∠C = 62°
Step-by-step explanation:
A cyclic quadrilateral is a four-sided polygon where all its vertices lie on the circumference of a single circle.
The opposite angles in a cyclic quadrilateral sum to 180°. In quadrilateral ABCD, angles B and D are opposite angles. Therefore, we can set the sum of their angle expressions equal to 180° and solve for x:
m∠B + m∠D = 180°
3x° + (x + 20)° = 180°
3x + x + 20 = 180
4x + 20 = 180
4x = 160
x = 40
To find the measure of angle C, set the sum of the expressions for opposite angles A and C equal to 180°, substitute x = 40, and solve for angle C:
m∠A + m∠C = 180°
(2x + 38)° + m∠C = 180°
(2(40) + 38)° + m∠C = 180°
(80 + 38)° + m∠C = 180°
118° + m∠C = 180°
m∠C = 180° - 118°
m∠C = 62°
Therefore, the measure of angle C is 62°.