Angles, Polygons & Parallel Lines — Year 8 Practice Questions
Work through these Year 8 practice questions on angles. Try each one before revealing the worked solution.
Questions
Two angles sit on a straight line. One is 115°. Find the other.
A triangle has angles 40° and 75°. Find the third angle.
Two parallel lines are crossed by a transversal. One angle is 70°. Find the corresponding angle.
Find the co-interior angle to an angle of 110° between two parallel lines.
Work out the sum of the interior angles of a pentagon.
Find the size of one interior angle of a regular hexagon.
Each exterior angle of a regular polygon is 40°. How many sides does it have?
An angle and its co-interior partner are equal. What is the size of each angle?
Answers & Worked Solutions
Question 1 Solution
Step 1: Angles on a straight line add to 180°.
Step 2: 180 − 115 = 65°.
Answer: 65°
Question 2 Solution
Step 1: Angles in a triangle add to 180°.
Step 2: 180 − 40 − 75 = 65°.
Answer: 65°
Question 3 Solution
Step 1: Corresponding angles are equal.
Step 2: So the angle is 70°.
Answer: 70°
Question 4 Solution
Step 1: Co-interior angles add to 180°.
Step 2: 180 − 110 = 70°.
Answer: 70°
Question 5 Solution
Step 1: Use 180 × (n − 2) with n = 5.
Step 2: 180 × 3 = 540°.
Answer: 540°
Question 6 Solution
Step 1: Interior sum = 180 × (6 − 2) = 720°.
Step 2: Regular, so divide by 6: 720 ÷ 6 = 120°.
Answer: 120°
Question 7 Solution
Step 1: Exterior angles add to 360°.
Step 2: 360 ÷ 40 = 9 sides.
Answer: 9 sides
Question 8 Solution
Step 1: Co-interior angles add to 180°.
Step 2: If they are equal, each is 180 ÷ 2 = 90°.
Answer: 90°
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