In the given diagram, \(\bar{QT}\) and \(\bar{PR}\) are straight lines, ∠ ROS = (3n -...
MATHEMATICS
WAEC 2015
In the given diagram, \(\bar{QT}\) and \(\bar{PR}\) are straight lines, ∠ ROS = (3n - 20), ang; SOT = n, ∠ POL = m and ∠ QOL is a right angle. Find the value of n.
- A. 35°
- B. 40°
- C. 55°
- D. 60°
Correct Answer: A. 35°
Explanation
In the diagram, QOR + 2m(vertically opposite angles)
So, m + 90° + 2m = 180°
(angles on str. line)
3m = 180° - 90°
3m = 90°
m = \(\frac{90^o}{3}\)
= 30°
substituting 30° for m in
2m + 4n = 200° gives
2 x 30° + 4n = 200°
60° + 4n = 200°
4n = 200° - 60°
= 140°
n = \(\frac{140°}{4}\)
= 35°
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