the base of an isosceles triangle is 16 in. and the altitude is 15in. Find the radius of the inscribed circle.

Sagot :

To find the radius of inscribed circle in isosceles triangle:

1)  Find the leg of the triangle, using the Pythagorean Theorem:
     c² = a² + b²   , where c is the missing leg
     c² = 15² + (16/2)²
     c² = 225 + 64
     c² = 289
     
     [tex] \sqrt{c ^{2} } = \sqrt{289} [/tex]
     c = 17

2) Find the radius: 

leg = 17;  base = 16

radius = [tex] \frac{base}{2} \sqrt{} \frac{2(leg)-base}{2(leg)+base} [/tex]

radius = [tex] \frac{16}{2} \sqrt{ \frac{2(17)-16}{2(17)+16} } [/tex]

radius = [tex]8 \sqrt{ \frac{34-16}{34+16} } [/tex]

radius = [tex]8 \sqrt{ \frac{18}{50} } = 8 \sqrt{ \frac{9}{25} } [/tex]

radius = 8 (³/₅)

radius = 24/5

radius = 4.8 inches