Question

Triangle ABC has a perimeter 22cm

AB= 8 cm
BC= 5cm

By calculation, deduce whether triangle ABC is a right-angled triangle

Answer 1

ΔABC is not a right- angled triangle

Explanation:

Given AB = 8, BC = 5

Then AC = 22 - (8 + 5) = 22 - 13 = 9 cm

Using the converse of Pythagoras' identity

If the square of the longest side equals the sum of the squares of the other 2 sides then triangle is right.

AC² = 9² = 81

AB² + BC² = 8² + 5² = 64 + 25 = 89

81 ≠ 89, hence ΔABC is not right- angled