Two towers on top of two hills are 40 km apart. The line joining them passes 50 m above a hill halfway between the towers. What is the longest wavelength of radio waves, which can be sent between the towers without appreciable diffraction effects?

Two poles of height 3 m and 2m are erected upright on the ground and ropes are stretched from the top of each to the foot of the tower. Prove that this height would be the same whatever be the distance between the poles. .

Two poles are erected upright on the ground and ropes are stretched from the top of each to the foot of the tower. Taking the heights of the poles as 'a' and 'b' and height above the ground of the point where the ropes cross each other as h, find the relation between a,b and h. .

Two children of same height standing on either sides of a tower, looks the top of tower at an elevation of 40^circ , 55^circ . The distance between the children is 25 metres. Height of the chlidren is 1.5 metres. a) Draw a rough figure showing the givën measurements. b) Calculate the height of the tower. [sin 40^circ =0.64, sin 55^circ =0.82, cos 40^circ =0.77, cos 55^circ =0 .57, tan 40^circ =0.89, tan 55^circ =1.43]