Вопрос:

Given that AB = 52, calculate the perimeter of triangle ABC.

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Ответ:

Analysis:

  • The image shows a right-angled triangle ABC.
  • A circle is inscribed within the triangle.
  • The points of tangency are labeled K, O, and C. This labeling seems incorrect; typically, points of tangency are on the sides.
  • Let's assume K is the point of tangency on side AC, and O is the point of tangency on side BC. The label 'O' is also used for the center of the circle. This is a contradiction. Let's assume the labels K and a point on BC (let's call it L) and a point on AB (let's call it M) are the points of tangency.

However, the diagram shows a right angle at C. The circle is tangent to AC at K, and to BC at O. It is also tangent to AB at some point (not clearly labeled, but the radius from the center to this point would be perpendicular to AB).

The diagram also shows the radius of the inscribed circle as 8.

In a right-angled triangle with an inscribed circle, the radius 'r' is related to the sides 'a', 'b', 'c' (where 'c' is the hypotenuse) by the formula:

r = (a + b - c) / 2

Also, in a right-angled triangle, if the points of tangency on the legs are K on AC and O on BC, and the center is I, then CKOI forms a square, so CK = CO = r.

From the diagram, the radius is given as 8. So, r = 8.

Let AC = b and BC = a. Since it's a right-angled triangle at C, AB = c is the hypotenuse.

So, CK = 8 and CO = 8.

Therefore, AC = b = AK + KC = AK + 8.

And BC = a = BO + OC = BO + 8.

From the properties of tangents from a vertex:

  • AK = AM (where M is the tangency point on AB)
  • BO = BM (where M is the tangency point on AB)

So, AC = AK + 8, and BC = BO + 8.

The hypotenuse AB = c = AM + MB = AK + BO.

We are given AB = 52.

So, AK + BO = 52.

The perimeter of triangle ABC is P = a + b + c.

P = BC + AC + AB

P = (BO + 8) + (AK + 8) + (AK + BO)

P = 2 * AK + 2 * BO + 16

P = 2 * (AK + BO) + 16

Since AK + BO = 52, we substitute this value:

P = 2 * (52) + 16

P = 104 + 16

P = 120.

Ответ: 120

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