What is the measure of the indicated angle ?

72

unknown angle suppose x

108+x=180(co interior angle)

x=180-108

x=72

a complex number is a number that can be expressed in the form a + bi, where a and b are real numbers, and i is a solution of the equation x2 = −1. because no real number satisfies this equation, i is called an imaginary number. has no real solution, since the square of a real number cannot be negative.