Checking and securing understanding of congruent triangles (RHS)
I can understand and use the criteria by which triangles are congruent (RHS).
- Year 10
Checking and securing understanding of congruent triangles (RHS)
I can understand and use the criteria by which triangles are congruent (RHS).
Lesson details
Key learning points
- For a right-angled triangle, you need the hypotenuse and one other side length to prove congruence.
- Right-angled triangles, by definition, have a right-angle.
- There is a special relationship between the sides in a right-angled triangle.
Keywords
Congruent - If one shape can fit exactly on top of another using rotation, reflection or translation, then the shapes are congruent.
Similar - Two shapes are similar if the only difference between them is their size. Their side lengths are in the same proportions.
Pythagoras' theorem - Pythagoras’ theorem states that the sum of the squares of the two shorter sides of a right-angled triangle is equal to the square of the hypotenuse.
Common misconception
Pupils may make incorrect assumptions about diagrams containing a right angle.
Remind pupils that they cannot assume there is a right angle, just because two line segments look as if they are perpendicular to each other.
Licence
Prior knowledge starter quiz
6 Questions
Q1.Two shapes will always be congruent if...
Q2.Two triangles are guaranteed to be congruent if...
Q3.Are these two triangles congruent? Explain your answer.

Q4.These two triangles are congruent. Match each side length to its value.

$$w$$ - 14.2 cm
$$y$$ - 16.3 cm
$$z$$ - 11.8 cm
Q5.Given these two triangles are congruent, the angle marked $$x$$ is °.

Q6.ABCD is a rhombus. Select all the statements needed to show that triangles ABD and BCD are congruent using the ASA congruence condition.

Assessment exit quiz
6 Questions
Q1.Pythagoras’ theorem states that the sum of the squares of the two shorter sides of a right-angled triangle is equal to the square of the .
Q2.The lengths of the 3 edges of some triangles are given. Select all the right-angled triangles.
Q3.A right-angled triangle has a hypotenuse of 17 m. Select the possible lengths of the two shorter sides.
Q4.Which of these pairs of triangles are congruent?




Q5.Triangle ABC and triangle DEF are congruent and AB > BC. The length of the side $$x$$ is cm.

Q6.Match each letter which the correct statement to complete the proof that triangle DAC and triangle ABC are congruent.

a - 90°
b - AC
c - BC
d - RHS