In the diagram below, |XR| = |RY| = |YZ| and ∠XRY = ∠YRZ = 62°,

MATHEMATICS
WAEC 1999

In the diagram below, |XR| = |RY| = |YZ| and ∠XRY = ∠YRZ = 62°, Calculate ∠XYZ

  • A. 50°
  • B. 62°
  • C. 112°
  • D. 115°

Correct Answer: D. 115°

Explanation

In triangle RXY, < RXY = < RYX (base angles of an isosceles triangle)

\(\implies\) 180° - 62° = 2 < RYX

118° = 2 < RYX \(\implies\) < RYX = 59°

In triangle RYZ, < RZY = 62° (base angles of an isosceles triangle)

\(\therefore\) < RYZ = 180° - (62° + 62°)

= 180° - 124° = 56°

\(\therefore\) < XYZ = 56° + 59°

= 115°



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