What this quiz covers

Grade 9 Congruent Triangles Quiz 1 draws its questions at random from 33 questions across these topics:


Worked examples

A few of the question types, with full solutions, so you know what to expect.

The four conditions. How many conditions can be used to prove that two triangles are congruent?

  1. Two
  2. Three
  3. Four
  4. Five

Answer: Four

There are exactly four: S,S,S · S,∠,S · ∠,∠,S · R,H,S.

Any one of them on its own is enough to prove congruency.

The four conditions. What does it mean when we say two triangles are CONGRUENT?

  1. They have the same shape but different sizes
  2. They are exactly the same shape AND the same size
  3. They have the same area
  4. They both contain a right angle

Answer: They are exactly the same shape AND the same size

Congruent triangles fit exactly on top of each other.

Every pair of corresponding sides is equal and every pair of corresponding angles is equal.

Same shape but DIFFERENT size is similar, not congruent.

The four conditions. Which symbol means 'is congruent to'?

  1. =

Answer: ≡

≡ means congruent — identical in shape and size.

≈ means approximately equal, = means equal in value, and ∥ means parallel.

The four conditions. The diagram shows two triangles with three pairs of sides marked equal. Which condition proves they are congruent?

  1. S, S, S
  2. S, ∠, S
  3. ∠, ∠, S
  4. R, H, S

Answer: S, S, S

Three pairs of corresponding SIDES are marked equal — one tick, two ticks and three ticks.

No angles are needed: if all three sides match, the triangles must be congruent.

The four conditions. The diagram shows two sides and the angle BETWEEN them marked equal. Which condition applies?

  1. S, S, S
  2. S, ∠, S
  3. ∠, ∠, S
  4. R, H, S

Answer: S, ∠, S

Two pairs of sides are marked, and the equal angle lies BETWEEN those two sides.

An angle between two sides is called the INCLUDED angle.