Cambridge International Mathematics

Assumed Knowledge (Geometry and graphs) 9

1 Construct a triangle which has sides of length:

a 2 cm, 3 cm and 3 cm b 2 cm, 3 cm and 4 cm

c 2 cm, 3 cm and 5 cm d 2 cm, 3 cm and 7 cm.

2 Copy and complete:

“The sum of the lengths of any two sides of a triangle must be ............ the length of the third side”.

3 Draw a triangle ABC with all sides greater

than 6 cm in length and with the angles

at A, B and C being 60 o, 50 oand 70 o

respectively.

Place a ruler and set

square as shown in the

figure. Slide the set square

along the ruler to the left,

keeping the ruler firmly in

place.

a Why does the hypotenuse of the set

square produce lines parallel to BC?

b Locate X on AB and Y on AC such that

XY=4cm.

You should now have a triangle which has angles of 60 o, 50 o

and 70 o, and where the side opposite the 60 oangle is 4 cm long.

In mathematics we use the termcongruentto describe things which have the same shape and size. The

closest we get to congruence in humans is identical twins.

1 Which of the following figures are congruent?

ABCDE

2 Which of the following geometric figures are congruent?

ABCDEFGH

IJKLMNO

F CONGRUENCE [4.1]

X Y

B C

A

60°

50° 70°

slide

EXERCISE E

EXERCISE F.1

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