HOTS Mathematics Primary 6 Angles

In the figure, AB is parallel to CD. In triangle ABC, angle ABC = 65° and angle ACD = 38°. Find angle BAC.

A 77°
B 103°
C 75°
D 115°
Show Worked Solution

Worked Solution

Step 1: Identify the alternate interior angles. AB ∥ CD and AC is a transversal. Angle ACD = angle BCA = 38° (alternate interior angles). Step 2: Apply the angle sum of a triangle. Angle BAC + angle ABC + angle BCA = 180° Angle BAC + 65° + 38° = 180° Angle BAC + 103° = 180° Angle BAC = 180° − 103° Angle BAC = 77°

Correct answer: 77°

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