Question

Find the radius of the incircle of a triangle whose sides are 15 , 20 , 25.​

Answer 1

Answer:

5

Step-by-step explanation:

From the given lengths we find that it is a right angled triangle by pythagoras theorem

⇒15^2+20^2=25^215

2

+20

2

=25

2

⇒225+400=625225+400=625

For finding the radius of incircle, we use the formula

Radius of incircle= Area of triangle / semi perimeter of triangle

(Note: Semi perimeter is half the perimeter)

We know that,

Area of triangle=\frac{1}{2}*15*20=150=

2

1

∗15∗20=150

Semi perimeter=\frac{1}{2}*(15+20+25)=30=

2

1

∗(15+20+25)=30

Hence,

Radius of incircle=\frac{150}{30}=5=

30

150

=5