[discia] GCSE Maths › Geometry & Measures › Congruent Triangles

Congruent Triangles

discia.org 10 questions · 21 marks
Name Date
  1. Either paper 1 mark
    Shapes A, B, C and D are drawn on a square grid. Shape A xy Shape B xy Shape C xy Shape D xy Which two shapes are congruent? Circle your answer.
    B and AC and DB and CD and A
    Show answer
    D and A
    Another like this
  2. Either paper 1 mark

    Here are two triangles.

    14 cm10 cm90° 14 cm10 cm90°

    The triangles are congruent. Circle the reason why these triangles are congruent.

    ASA    RHS    SAS    SSS

    Show answer
    RHS
    Another like this
  3. Either paper 1 mark

    Here are four triangles, A, B, C and D. The diagrams are not drawn accurately.

    Triangle A

    9 cm48°100°

    Triangle B

    9 cm48°100°

    Triangle C

    9 cm48°32°

    Triangle D

    11 cm48°100°

    Which two triangles are congruent? Give the two letters.

    Show answer
    A and C
    Another like this
  4. Either paper 3 marks

    This shape is made from two triangles and four parallelograms with the same acute angle. The two parallelograms in each row are congruent to each other, but the top row need not be the same size as the bottom row. The shape has two rows, one above the other. Each row is a parallelogram, a triangle and a parallelogram side by side. The diagram shows one row and is not drawn accurately.

    The acute angle of each parallelogram is between 36° and 40°.

    For each statement, tick the correct box: must be true, could be true or must be false.

    (a)

    The angle between the two sloping sides of a triangle is larger than each of its other two angles.

    (b)

    The triangles are equilateral.

    (c)

    The triangles are right-angled.

    Show answer
    (a) Must be true
    (b) Must be false
    (c) Must be false
    Another like this
  5. Either paper 3 marks

    \(ABCD\) is a quadrilateral. The diagonal \(AC\) has been drawn.

    ABCD

    \(AB = AD\), as the dashes show, and \(CB = CD\).

    (a)

    Using only the information given, write down the condition (SSS, SAS, ASA or RHS) that shows triangle \(ABC\) and triangle \(ADC\) are congruent.

    (b)

    Hence write down the angle that must be equal to angle \(BAC\).

    Show answer
    (a) SSS
    (b) \(\angle DAC\)
    Another like this
  6. Either paper 2 marks

    Triangle \(ABC\) and triangle \(PQR\) are congruent, with \(A\) matching \(P\), \(B\) matching \(Q\) and \(C\) matching \(R\).

    \(AB = PQ\), \(AC = PR\) and \(\angle BAC = \angle QPR\).

    In triangle \(ABC\), \(AB = 21\) cm, \(BC = 20\) cm and \(AC = 29\) cm.

    (a)

    Write down the condition (SSS, SAS, ASA or RHS) that the three facts above show.

    (b)

    Write down the length of \(PR\).

    Show answer
    (a) SAS
    (b) \(29\ \text{cm}\)
    Another like this
  7. Either paper 3 marks

    \(ABC\) is a triangle with \(AB = AC = 13\) cm and \(BC = 12\) cm.

    The dashed line runs from \(A\) to the point \(M\) on \(BC\), and \(AM\) is perpendicular to \(BC\).

    BCA
    (a)

    Using only the information given, write down the condition (SSS, SAS, ASA or RHS) that shows triangle \(ABM\) and triangle \(ACM\) are congruent.

    (b)

    Hence state the length of \(BM\).

    Show answer
    (a) RHS
    (b) \(6\ \text{cm}\)
    Another like this
  8. Either paper 2 marks

    Triangle \(ABC\) has \(AB = 14\) cm, \(BC = 15\) cm and \(\angle BCA = 62^\circ\).

    Triangle \(PQR\) has \(PQ = 14\) cm, \(QR = 15\) cm and \(\angle QRP = 62^\circ\).

    Are the two triangles necessarily congruent?

    Write Yes or No, and give a reason for your answer.

    Show answer
    No, because the angle given does not lie between the two sides given, and two different triangles can be drawn from that information
    Another like this
  9. Either paper 3 marks

    \(ABCD\) is a parallelogram with \(AB = 14\) cm and \(BC = 6\) cm. The diagonal \(AC\) has been drawn.

    Angle \(ABC = 78^\circ\).

    14 cm6 cmABCDDiagram NOT accurately drawn
    (a)

    Write down the condition (SSS, SAS, ASA or RHS) that shows triangle \(ABC\) and triangle \(CDA\) are congruent.

    (b)

    State the size of angle \(CDA\).

    Show answer
    (a) SSS
    (b) \(78^\circ\)
    Another like this
  10. Either paper 2 marks

    In triangle \(ABC\), angle \(ABC = 48^\circ\), angle \(BCA = 69^\circ\) and \(BC = 7\) cm.

    In triangle \(PQR\), angle \(PQR = 48^\circ\), angle \(QRP = 69^\circ\) and \(QR = 7\) cm.

    Are the two triangles congruent, similar but not congruent, or neither?

    You must give a reason for your answer.

    Show answer
    congruent, because two pairs of angles are equal and so are the sides between them, which is ASA
    Another like this
discia.org Congruent Triangles · sheet 1
Answers Congruent Triangles · sheet 1
  1. D and A
  2. RHS
  3. A and C
  4. (a) Must be true
    (b) Must be false
    (c) Must be false
  5. (a) SSS
    (b) \(\angle DAC\)
  6. (a) SAS
    (b) \(29\ \text{cm}\)
  7. (a) RHS
    (b) \(6\ \text{cm}\)
  8. No, because the angle given does not lie between the two sides given, and two different triangles can be drawn from that information
  9. (a) SSS
    (b) \(78^\circ\)
  10. congruent, because two pairs of angles are equal and so are the sides between them, which is ASA
discia.org Congruent Triangles · sheet 1