Question

the lengths of the sides of triangles are given below. which of them are right- angled? a) 15cm, 20cm, 25cm b) 9cm, 12cm, 16cm​

Answer 1

Answer:

Step-by-step explanation:

(i) Let us assume the largest value is the hypotenuse side c=25cm

Then, by Pythagoras theorem

c  

2

=a  

2

+b  

2

 

25  

2

=15  

2

+20  

2

 

625=225+400

625=625

The sum of square of two side of triangle is equal to the square of third side

∴ the given triangle is right-angled triangle

(ii) Let us assume the largest value is the hypotenuse side c=16cm

Then, by Pythagoras theorem

c  

2

=a  

2

+b  

2

 

16  

2

=9  

2

+12  

2

 

256=81+144

256



=225

The sum of square of two side of triangle is not equal to the square of third side

∴ the given triangle is not a right-angled triangle