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The two sides of a right triangle containing the right angle measure 3 cm and 4 cm. The radius of the in circle of the triangle is :
-
- 3.5 cm
- 1.75 cm
- 1 cm
- 0.875 cm
- None of these
Correct Option: C
First method :-
If the in circle of a triangle ABC touches BC at D, then |BC - CD| = |AB - AC|
In our case, AC = 5, AB = 3
⇒ AC – AB = 2
∴ CD – BD = 2
In our case, BC = 4
⇒ BD + BD = 4 and – BD + DC = 22
⇒ CD = 3
⇒ BD = 1 = OE = Radius of the in circle.
second method :-
We know that , In right angle triangle
Here , a = 3 cm , b = 4 cm and c = 5 cm
We know that ,
| The radius of the incircle = | a + b - c |
| 2 |
| The radius of the incircle = | 3 + 4 - 5 | = | 2 |
| 2 | 2 |
∴ The radius of the incircle = 1 cm
