# CBSE Class 10 – Mathematics: Questions and Answers Chapter – 10 Circles Part 10

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**Question 24:**

Find the unknown length .

**Answer:**

PT is tangent to a circle and PAB is a secant.

**Question 25:**

In the given figure, OD is perpendicular to the chord AB of a circle whose center is O. If BC is a diameter, find .

**Answer:**

Since BC is a diameter

Also

**Question 26:**

In the given figure, and are tangents from to the circle with centre O. R is a point on the circle such that ARB is a tangent to the circle prove that .

**Answer:**

In the given figure, and are tangents from external point

**Question 27:**

Prove that the segment joining the points of contact of two parallel tangents, passes through the center.

**Answer:**

Given two parallel tangents and RS of a circle with centre

Draw line .

i.e.,

**Question 28:**

In figure, if , , then length of AB is

**Answer:**