Mark a point Q outside the circle C(0,3.5) such that OQ = 7cm. Draw two tangents to the given circle from point Q. Measure their lengths. Write steps of construction

A pair of tangents to the given circle can be constructed as follows.

Step 1

Taking any point O of the given plane as centre, draw a circle of 3.5 cm radius. Locate a point Q, 7 cm away from O. Join OQ.

Step 2

Bisect OQ. Let M be the mid-point of QO.

Step 3

Taking M as centre and MO as radius, draw a circle.

Step 4

Let this circle intersect the previous circle at point S and R.

Step 5

Join QS and QR. QS and QR are the required tangents.
Measure the length of the tangents with the help of scale.