Home
Class 12
MATHS
A tower subtends angles alpha,2alpha,3al...

A tower subtends angles `alpha,2alpha,3alpha` respectively, at point `A , B ,a n dC` all lying on a horizontal line through the foot of the tower. Prove that `(A B)/(B C)=1+2cos2alphadot`

A

`1+2cos 2alpha`

B

`1-2cos2alpha`

C

`1+3cos 2alpha`

D

`1-3cos2alpha`

Text Solution

Verified by Experts

The correct Answer is:
A
Promotional Banner

Similar Questions

Explore conceptually related problems

A tower subtends angle theta, 2theta, 3theta at the three points A,B and C respectively lying on a horizontal line through the foot of the tower. Then AB/BC is equal to

If a tower subtends angles theta, 2 theta and 3 theta at three points A,B,and C respectively, lying on the same side of a horizontal line through the foot of the tower, show that (AB)/(BC) (cot theta- cot 2 theta)/(cot 2 theta - cot 3 theta).

The angle of elevation of the top of a T.V. tower from three points A,B,C in a straight line in the horizontal plane through the foot of the tower are alpha, 2alpha, 3alpha respectively. If AB=a, the height of the tower is

A tower subtends an angle alpha at a point A in the plane of its base and the angle of depression of the foot of the tower at a point b metres just above A is beta . Prove that the height of the tower is btanalphacotbeta .

A tower of height b subtends an angle at a point 0 on the ground level through the foot of the tower and at a distance a from the foot of the tower. A pole mounted on the top of the tower also subtends an equal angle at 0. The height of the pole is

A tower subtends an angle α at a point on the same level as the root of the tower and at a second point, b meters above the first, the angle of depression of the foot of the tower is β. The height of the tower is

The angle of elevation of the top of a tower standing on a horizontal plane from a point A is alpha . After walking a distance d towards the foot of the tower the angle of elevation is found to be beta . The height of the tower is (a) d/(cotalpha+cotbeta) (b) d/(cotalpha-cotbeta) (c) d/(tanbeta-t a nalpha) (d) d/(tanbeta+tanalpha)

A vertical tower PQ subtends the same anlgle of 30^@ at each of two points A and B ,60 m apart on the ground .If AB subtends an angle of 120^@ at p the foot of the tower ,then find the height of the tower .

If the angles of elevation of the top of a tower from three collinear points A, B and C, on a line leading to the foot of the tower, are 30^0 , 45^0 and 60^0 respectively, then the ratio, AB : BC, is : (1) sqrt(3):1 (2) sqrt(3):sqrt(2) (3) 1:sqrt(3) (4) 2"":""3

A tower P Q stands at a point P within the triangular park A B C such that the sides a , ba n dc of the triangle subtend equal angles at P , the foot of the tower. if the tower subtends angles alpha,betaa n dgamma,a tA , Ba n dC respectively, then prove that a^2(cotbeta-cotgamma)+b^2(cotgamma-cotalpha)+a^2(cotalpha-cotbeta)=0