Question

In the given figure : ∠b = 2a + 15 and ∠c = 3a + 5; find the values of b and c.

Answer 1

∵ Sum of angles of quadrilateral = 360°

70° + a + 2a + 15 + 3a + 5 = 360°

6a + 90° = 360°

6a = 270°

a = 45°

∴ b = 2a + 15 = 2 x 45 + 15 = 105°

c = 3a + 5 = 3 x 45 + 5 = 140°

Hence ∠b and ∠c are 105° and 140°