ce a.maths differentiation

1.FIND THE MAXIMUM
AREA OF A RECTANGLE
WHICH CAN BE INSCRIBED
IN A CIRCLE OF RADIUS 5 cm.

3.A and D are two towns is
due east of main road BC
with ∠ABC and ∠BCD = 90°
and BA=2km., CD= 3km
and BC=10km. A road APD
is to be made to join
A and D to the main road.
Where should the location
of P be in order that the
length of the road is its smallest?