Congruent shapes
2 shapes that are the same size and the same shape are congruent.
Shapes A, B, E and G are congruent. They are identical in size and shape.
Congruent triangles
For 2 triangles to be congruent, 1 of 4 criteria need to be met.
The 3 sides are equal (SSS: side, side, side)
2 angles are the same and a In similar shapes, corresponding sides are in the same ratio. is the same (ASA: angle, side, angle)
2 sides are equal and the angle between the 2 sides is equal (SAS: side, angle, side)
A right angle, the The longest side of a right-angled triangle, which is opposite the right angle, is called the hypotenuse. and a corresponding side are equal (RHS: right angle, hypotenuse, side)
Example one
State whether the 2 triangles are congruent. Give a reason to support your answer.
Yes - SSS, the 3 sides are equal.
Example two
State whether the 2 triangles are congruent. Give a reason to support your answer.
Yes - RHS.
Question
State whether the 2 triangles are congruent. Give a reason to support your answer.
No - in the left hand diagram the 7 cm length is between the angles 40° and 60°. In the right hand diagram it is not.
