The angle of elevation of a cloud from a point
h meters above the surf ace of a lake i s
30° and the angle of depression of its reflection
is 60°. Then the height of the cloud above the
surface of the lake is –
The radi i of two concentric circles are
17 cm and 10 cm respectively. A straight line
ABCD intersects the larger circle at the point
A and D and intersects the smaller circle at
the point B and C. If BC = 12 cm, then the
length of AD (in cm) is –
