Question

Abcd is a quadrilateral. three of the angles of abcd measure 100°, 87°, and 106°, respectively. find the measure of the missing angle.
a. 67°
b. 74°
c. 80°
d. 87°

Answer 1

A quadrilateral in total is 360 degrees.
(x = the missing length)

100 + 87 + 106 + x = 360
293 + x = 360
-293       -293
x = 67 degrees.

The answer to your question is option A, 67 degrees.