Q99 of 113 Page 128

In Fig. 5.52, AE || GF || BD, AB || CG || DF and ∠CHE = 120°. Find ∠ABC and ∠CDE.

∠ HCB = ∠CHE = 120⁰ (Alternate Interior angles)

∠ HCB + ∠ ABC = 180⁰ ( Co interior angles)

⇒ ∠ ABC = 60⁰

∠ HCB = ∠CDE = 120⁰ (Corresponding angle)

∠ ABC = 60⁰ and ∠CDE = 120⁰

Two angles are making a linear pair. If one of them is one-third of the other, find the angles.

Measures (in degrees) of two supplementary angles are consecutive odd integers. Find the angles.

100

In Fig. 5.53, find the value of ∠BOC, if points A, O and B are collinear.

101

In Fig. 5.54, if l ||m, find the values of a and b.