An angle greater than 180° and less than a complete angle is called ______.

in Fig. 2.12,

∠BAC = 90° and AD ⊥ BC.

The number of right triangles in the figure is

In Fig. 2.13, PQ ⊥ RQ, PQ = 5 cm and QR = 5 cm. Then ∆ PQR is

The number of diagonals in a hexagon is _____.

A pair of opposite sides of a trapezium are ________.