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Class 6 Maths — Understanding elementary shapes

Classify angles by size, triangles by their sides and their angles, and tell flat shapes from solid ones.

Name: ________________________

Before you start

Four angles, drawn side by side and getting wider as you go. Find out what each one is called.

1234
  1. 1. Acute
  2. 2. Right angle
  3. 3. Obtuse
  4. 4. Straight

Acute is under 90°, obtuse is over it, and the straight one is a half turn — 180°, which is why it stopped looking like a corner at all.

  1. 1.The angles of a triangle add up to 180°. Two of them are 55° and 65°. How big is the third, in degrees?

  2. 2.A triangle has sides of 5 cm, 5 cm and 8 cm. How many of its sides are equal in length?

  3. 3.Sort each shape by whether it is flat or solid.

    Groups: Flat shape · Solid shape

    • Cylinder
    • Circle
    • Sphere
    • Triangle
    • Square
    • Cube

  4. 4.An angle of 200° is which kind of angle?

    • a) Obtuse
    • b) Straight
    • c) Acute
    • d) Reflex

  5. 5.Match each angle to the name for its size.

    • 45°
    • 90°
    • 120°
    • 180°
    • 300°
    • Obtuse
    • Straight
    • Right
    • Reflex
    • Acute

  6. 6.All three angles of an equilateral triangle are equal, and they add up to 180°. How big is each one, in degrees?

  7. 7.This triangle has one right angle. Tap the corner where it is.

    Write the number of the part.

    123

  8. 8.A full turn is 360° and splits into four equal right angles. How many degrees is one right angle?

Answer key — Class 6 Maths — Understanding elementary shapes

  1. 1. 60
  2. 2. 2
  3. 3. Square → Flat shape; Cube → Solid shape; Circle → Flat shape; Sphere → Solid shape; Triangle → Flat shape; Cylinder → Solid shape
  4. 4. d) Reflex
  5. 5. 45° → Acute; 90° → Right; 120° → Obtuse; 180° → Straight; 300° → Reflex
  6. 6. 60
  7. 7. 2 — the bottom left corner
  8. 8. 90