Trigonometric l...

The area of the equilateral triangle which contains three coins of unity radius is

For a regular polygon, let r and R be the radii of the inscribed and the circumscribed circles. A false statement among the following is

The angle of elevation of the top of a tower at a point on the ground is 30^o. If on walking 20 metres toward the tower, the angle of elevation become 60^o, then the height of the tower is

The angle of elevation of tower at a point distant d metres from it base is 30^o. If the tower is 20 metres high, then the value of d is

The angle of elevation of the top of the tower observed from each of the three points A, B, C on the ground, forming a triangle is the angle α. If R is the circum radius of the triangle ABC, then the height of the tower is

The angle of elevation of the top of a tower from a point A due south of the tower is α and from a point B due east of the tower is β. If AB = d, then the height of the tower is

A person standing on the bank of a river observes that the angle subtend by a tree on the opposite bank is 60^o. When he retires 40 metres from the bank, he finds the angle to be 30^o. The breadth of the river is

A vertical pole consists of two parts, the lower part being one third of the whole. At a point in the horizontal plane through the base of the pole and distance 20 metres from it, the upper part of the pole subtends an angle whose tangent is 1/2. The possible heights of the pole are