Question

If the distance between the centres of two circles of radii 3, 4 units is 25, then the length of their transverse common tangent is

• A. $24$
• B. $12$
• C. $2$6
• D. $13$

Answer 1

The correct option is A $24$

Length of transverse common tangent
$=\sqrt{d^2-(r_1+r_2{)}^2}$
Given $d=25$ and $r_1=4$ & $r_2=3$
$\therefore L=\sqrt{(25{)}^2-(7{)}^2}$
$L=24$