The measures of two angles of a triangle are 25° and 87°. Is the triangle acute, right, or obtuse? Explain.

A.
Acute; the measure of the third angle is 68°. So all three angles are acute.

B.
Acute; the measure of the third angle is 78°. So all three angles are acute.

C.
Obtuse; 25° + 87° = 112° and 112° is an obtuse angle.

D.
Right; 25° + 87° = 112° and 202°
−
-
112° = 90°.