A circle with a radius of 1 cm is inscribed in a right-angled triangle, the angle ABC is 60. Find the area of the triangle.
May 2, 2021 | education
| From the point O, the center of the circle, we will construct the radii OK, OH and OM to the points of tangency.
The СKOН quadrangle is a square, then CH = R = 1 cm.
Segments BН and BM are tangent to the circle drawn from one point, then ОВ is the bisector of the angle ABC, which means the angle ОBН = 60/2 = 30.
In a right-angled triangle ОBН, tg30 = ОН / BН.
BH = OH / tg30 = 1 / (1 / √3) = √3 cm.
Then ВС = СН + ВН = 1 + √3 cm.
In a right-angled triangle ABC tgB = tg60 = AC / BC.
AC = BC * tg60 = (1 + √3) * √3 = 3 + √3 cm.
Then Savs = AC * BC / 2 = (1 + √3) * (3 + √3) / 2 = (6 + 4 * √3) / 2 = 3 + 2 * √3 cm2.
Answer: The area of the triangle is 3 + 2 * √3 cm2.
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