Angles on a straight line
Name: _____________________ Date: __________
Show your thinking with numbers, words, or a drawing.
1. The angles sit on a straight line. Find the angle marked with a question mark. The diagram is not drawn to scale.
2. The angles sit on a straight line. Find the angle marked with a question mark. The diagram is not drawn to scale.
3. The angles sit on a straight line. Find the angle marked with a question mark. The diagram is not drawn to scale.
4. The angles sit on a straight line. Find the angle marked with a question mark. The diagram is not drawn to scale.
5. The angles sit on a straight line. Find the angle marked with a question mark. The diagram is not drawn to scale.
Answer key · Angles on a straight line
1. 65
Angles on a straight line add up to 180°.
180 − 115 = 65, so the missing angle is 65°.
2. 40
Angles on a straight line add up to 180°.
180 − 140 = 40, so the missing angle is 40°.
3. 25
Angles on a straight line add up to 180°.
180 − 155 = 25, so the missing angle is 25°.
4. 100
Angles on a straight line add up to 180°.
180 − 80 = 100, so the missing angle is 100°.
5. 150
Angles on a straight line add up to 180°.
180 − 30 = 150, so the missing angle is 150°.
Try it together
Choose a question from the printable. Use objects or a drawing to show your thinking, then explain your method to someone at home.