The figure is not drawn to scale. ∠NMP = 41°, NM = NP and MS//NR. Given that ∠m is
13 of ∠j and ∠m is 4 times of ∠k, find
- ∠m
- ∠i
(a)
m : j = 1 : 3
j = 3 m
k : m = 1 : 4
j = 3 x 4= 12
j : k : m = 12 : 1 : 4
∠NPM = 41° (Isosceles triangle)
∠MPQ
= 180° - 41°
= 139° (Angles on a straight line)
1 u + 4 u + 12 u + 139° = 360° (Sum of angles in a quadrilateral)
17 u = 360° - 139° = 221°
1 u = 221 ÷ 17 = 13°
∠m
= 4 x 1 u
= 4 x 13°
= 52°
(b)
∠NPM = ∠NMP = 41° (Isosceles triangle)
∠PTR = ∠PMS = 52° (Corresponding angles, MS//NR)
∠i
= 52° - 41°
= 11° (Exterior angle of a triangle)
Answer(s): (a) 52°; (b) 11°
