Advertisements
Advertisements
Question
Draw a circle at a radius of 4 cm. Take a point on it. Without using the centre at the circle, draw a tangent to the circle at point P.
Advertisements
Solution

Steps of Construction:
(i) Draw a chord PQ through the given point on the circle.
(ii) Take a point R on the circle and join P and Q to a point R.
(iii) Construct ∠ QPY = ∠ PRQ on the opposite sides of the chord PQ.
(iv) Produce YP to X' to get YPX as the required tangent.
Construct a tangent to the circle from an external point:
In this section we shall study the construction at tangent to a circle from an external point when its center is; (i) Know (ii) Unknown
Type (I). Construction at tangent to a circle from an external point when its centre is known.
Steps of Construction:
(i) Join the centre O of the circle to the given external point P i.e., join OP.
(ii) Draw right bisector of OP, intersecting OP at Q.
(iii) Taking Q as centre and OQ = PQ as radius, draw a circle to intersect the given circle at T and T'.

(iv) Join PT and PT' to get the required tangents as PT and PT'.
APPEARS IN
RELATED QUESTIONS
Draw a pair of tangents to a circle of radius 5 cm which are inclined to each other an angle of 60º.
In the figure given below, O is the centre of the circle and SP is a tangent. If ∠SRT = 65°,
find the value of x, y and z.

Draw a circle of radius 3.5 cm. Take two points A and B on one of its extended diameter, each at a distance of 5 cm from its center. Draw tangents to the circle from each of these points A and B.
Draw a circle with centre O and radius 2.5 cm. Take a point P at a distance of 6 cm from the centre. Using ruler and compasses only construct the tangents to the circle from the point P.
Draw a circle of radius 4 cm. From a point 6 cm away from its centre, construct a pair of tangents to the circle and measure their lengths.
In Figure 2, PQ is a chord of length 8 cm of a circle of radius 5 cm. The tangents at P and Q intersect at a point T. Find the length TP.

Use a ruler and a pair of compasses to construct ΔABC in which BC = 4.2 cm, ∠ ABC = 60°, and AB 5 cm. Construct a circle of radius 2 cm to touch both the arms of ∠ ABC of Δ ABC.
There is a circle with center O. P is a point from where only one tangent can be drawn to this circle. What can we say about P?
Construct a pair of tangents to a circle of radius 4 cm from a point P lying outside the circle at a distance of 6 cm from the centre.
Using ruler and compass construct a triangle ABC in which AB = 6 cm, ∠BAC = 120° and AC = 5 cm. Construct a circle passing through A, B and C. Measure and write down the radius of the circle.
