∠BED and ∠CEA are vertical angles, so that means they are equal to each other.
∠CEA = 88
∠CEB and ∠AED must equal the same since they are also vertical angles, so we will make them both = x in an equation.
All of these angles will add up to 360° because they form a quadrilateral.
88 + 88 + x + x = 360
Combine like terms.
176 + 2x = 360
Subtract 176 from 360.
2x = 184
Divide both sides by 2.
x = 92
Since ∠CEB is larger than 90°, it is an obtuse angle.
