(a) If the measures of ZR, ZS, and I sum to 180°, then one of the angles must
be obtuse.
Counterexample: m (b) If mWXZ= 60°, and point Y is in the interior of ZWXZ, then m ZWXY = 40°
and mYXZ= 20°.
Counterexample: mWXY = m ZYXZ = []
(c) If the area of a rectangle is 100, then the length is 10 and the width is 10.
Counterexample: length =width =
(d) If 21 and 22 are complementary angles, then one of them must have a
measure less than 45°.
Counterexample: mZ1 = . m 2 2 = 0