An isosceles triangle ABC is inscribed in a
circle when AB = AC = 20 cm and BC = 24 cm.
Find the radius of the circle.
Answers
Answer:
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Answer:
Step-by-step explanation:
let AM ⊥ BC (A-O-M)
BM = MC =1/2 BC ( perpendicular drawn from centre to chord bisects the chord)
In Δ AMB , by pythagoras theorem,
AB² = AM² + BM²
20² = AM² + 12²
400- 144 = AM²
AM²= 256
AM= 16 cm
OA=OB ( radii of same circle ) = x
and AM =16
∴ OM = 16- x
In Δ OMB , by pythagoras theorem,
OB² = OM² + BM²
x² = ( 16-x )² + 12²
x² = 256 +x² - 32x +144 [ since ( a-b )² = a² + b² - 2ab]
{since x² is common on both side , x² would be cancelled}
0= 256 - 32x + 144
0= 400 - 32x
32x = 400
x = = = = 12.5
∴ radius = 12 .5
DIAGRAM ↓