Angles (Copy)
Q1 (Non-Calculator)
Find the missing angle at a point if three angles are 90°, 120°, and 70°.
Solution:
Sum of angles at a point = 360°
Missing angle = 360 – (90 + 120 + 70)
Missing angle = 360 – 280
Missing angle = 80°
Answer:
80°
Q2 (Non-Calculator)
Two angles on a straight line are 65° and x°. Find x.
Solution:
Sum of angles on a straight line = 180°
x = 180 – 65
x = 115°
Answer:
115°
Q3 (Non-Calculator)
Angles ABC and CBD are vertically opposite. If angle ABC = 75°, find angle CBD.
Solution:
Vertically opposite angles are equal.
Angle CBD = 75°
Answer:
75°
Q4 (Non-Calculator)
In a triangle, two angles are 50° and 60°. Find the third angle.
Solution:
Sum of angles in a triangle = 180°
Third angle = 180 – (50 + 60)
Third angle = 180 – 110
Third angle = 70°
Answer:
70°
Q5 (Non-Calculator)
In a quadrilateral, three angles are 85°, 95°, and 100°. Find the fourth angle.
Solution:
Sum of angles in a quadrilateral = 360°
Fourth angle = 360 – (85 + 95 + 100)
Fourth angle = 360 – 280
Fourth angle = 80°
Answer:
80°
Q6 (Calculator)
Two parallel lines are crossed by a transversal. One corresponding angle is 68°. Find the other corresponding angle.
Solution:
Corresponding angles are equal.
Other corresponding angle = 68°
Answer:
68°
Q7 (Calculator)
Two parallel lines are crossed by a transversal. One alternate angle is 50°. Find the other alternate angle.
Solution:
Alternate angles are equal.
Other alternate angle = 50°
Answer:
50°
Q8 (Calculator)
Two co-interior angles are 110° and x°. Find x.
Solution:
Co-interior angles add to 180°.
x = 180 – 110
x = 70°
Answer:
70°
Q9 (Calculator)
Find the size of one exterior angle of a regular pentagon.
Solution:
Exterior angle = 360 ÷ 5
Exterior angle = 72°
Answer:
72°
Q10 (Calculator)
Find the size of one interior angle of a regular octagon.
Solution:
Interior angle = (n – 2) × 180 ÷ n
Interior angle = (8 – 2) × 180 ÷ 8
Interior angle = 6 × 180 ÷ 8
Interior angle = 1080 ÷ 8
Interior angle = 135°
Answer:
135°