Question

Find the value of the unknown interior angle x in the following figures:

Answer 1

(i) x + 50° = 115° (Exterior angle theorem)

x = 115° − 50° = 65°

(ii) 70° + x = 100° (Exterior angle theorem)

x = 100° − 70° = 30°

(iii) x + 90° = 125° (Exterior angle theorem)

x = 125° − 90° = 35°

(iv) x + 60° = 120° (Exterior angle theorem)

x = 120° − 60° = 60°

(v) x + 30° = 80° (Exterior angle theorem)

x = 80° − 30° = 50°

(vi) x + 35° = 75° (Exterior angle theorem)

x = 75º − 35º = 40°