Question 23
The figure shows three circles with centers $A$, $B$ and $C$ above a horizontal surface $L$. The smallest circle, with center $B$, is externally tangent to the other two circles. The circles with centers $A$ and $C$ both have radius $a$ cm, while the circle with center $B$ has radius $b$ cm.
The segment $AC$ is parallel to $L$, and $D$ is its midpoint. Given that $AD=y$ cm and the perpendicular distance from $D$ to $L$ is $h$ cm, express the perpendicular distance from $B$ to $L$ in terms of $a,b,h$ and $y$. The point $B$ lies above $D$, as shown.
The segment $AC$ is parallel to $L$, and $D$ is its midpoint. Given that $AD=y$ cm and the perpendicular distance from $D$ to $L$ is $h$ cm, express the perpendicular distance from $B$ to $L$ in terms of $a,b,h$ and $y$. The point $B$ lies above $D$, as shown.