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🔺 7th grade math · Shapes & Space

Angle puzzles and slices

Angles on a straight line add to 180°, a right angle is 90°, a triangle's three angles add to 180°. Angles across from each other where lines cross are equal. All the way around a point is 360°.

Worked example

Two angles sit next to each other on a straight line. One measures 30°. What does the other measure?
30°?
Answer: 150°
Angles on a straight line add to 180°. 180 − 30 = 150°.

For grown-ups: Draw triangles from conditions; cross-sections; angle relationships. Below: three problems to try with the worked answers, and a free printable sheet. Children can practise the same skill as a game, with no sign-up and no ads.

  • CCSS 7.G.A.2–3
What this practises, for teachers

Practices draw triangles from conditions; cross-sections; angle relationships (7.G.A.2–3). A printable sheet with its answer key, worked answers on the page, no accounts.

▶ Practise it

For your class

🖨️ Printable sheet and key

On the board with this skill:

Try three

  1. Two angles together make a right angle. One measures 40°. What does the other measure?
    40°?
    Show the answer and how
    Answer: 50°
    Angles that make a right angle add to 90°. 90 − 40 = 50°.
  2. Two angles together make a right angle. One measures 65°. What does the other measure?
    65°?
    Show the answer and how
    Answer: 25°
    Angles that make a right angle add to 90°. 90 − 65 = 25°.
  3. Two angles sit next to each other on a straight line. One measures 85°. What does the other measure?
    85°?
    Show the answer and how
    Answer: 95°
    Angles on a straight line add to 180°. 180 − 85 = 95°.

Before and after

Learn first: Shapes on a coordinate grid (6th)

Comes next: Slide, flip, turn, stretch (8th)

Name: ____________________Date: ____________Score: ____ / 12

Angle puzzles and slices (7th grade)

  1. Two angles sit next to each other on a straight line. One measures 20°. What does the other measure?
    20°?
  2. Two angles together make a right angle. One measures 10°. What does the other measure?
    10°?
  3. Two angles sit next to each other on a straight line. One measures 170°. What does the other measure?
    170°?
  4. Two angles sit next to each other on a straight line. One measures 80°. What does the other measure?
    80°?
  5. Two angles sit next to each other on a straight line. One measures 100°. What does the other measure?
    100°?
  6. Two angles sit next to each other on a straight line. One measures 135°. What does the other measure?
    135°?
  7. Two straight lines cross. One of the angles measures 20°. What does the angle directly across from it measure?
    20°?
  8. Two straight lines cross. One of the angles measures 125°. What does an angle right next to it measure?
    125°?
  9. Two angles of a triangle measure 47° and 36°. What does the third angle measure?
  10. Two straight lines cross. One of the angles measures 116°. What does an angle right next to it measure?
    116°?
  11. Two angles together make a right angle. One measures 85°. What does the other measure?
    85°?
  12. A triangle has two equal sides. Each of the two angles at the bottom of the equal sides measures 58°. What does the angle between the equal sides measure?

Answer key

  1. 160°
  2. 80°
  3. 10°
  4. 100°
  5. 80°
  6. 45°
  7. 20°
  8. 55°
  9. 97°
  10. 64°
  11. 5°
  12. 64°

More 7th grade skills: all 7th grade math skills, or every grade at math skills.