Question

draw two direct common tangents to two circles of radii 4 cm and 2cm whose centres are 8 cm apart measured the length of the tangents​

Answer 1

Answer:

PQ=

d

2

−(r

1

−r

2

)

2

PQ=

8

2

−2

2

PQ=7.75cm

Draw a line segment AB=15cm. Draw circle C1 with radius 4cm and centre as A. Draw circle C2 with radius 2cm and centre B

Draw circle C3 with radius (R

1

−R

2

=4−2=2cm and centre A. B is the external point to circle C3. Draw perpendicular bisector of AB and mark its midpoint M

With M as centre and AM as radius construct a circle C4

C4 cuts C3 at two points E and F. Join AE and AF

Extend AE to meet C1 at P and AF to meet C1 at R

Draw BQ∥AP and BS∥AR

Join PQ and RS. PQ and RS are required direct tangents.