Construct tangents to the circle from point B with radius 3.5 cm and centre A. Point B is at a distance 8.5 cm from the centre.

 Steps of construction:

1. Draw a circle with centre ‘A’ and radius 3.5 cm . Take a point B such that AB = 8.5 cm.
2. Obtain the midpoint M of seg AB. (8.5/2=4.25 cm) by using scale or by using perpendicular bisector method.
3. Draw a circle with M as centre and BM as radius.
4. Let C and D be the points of intersection of these two circles.
5. Draw rays BC and BD which are the required tangents.