Dear CR4 Members,

To-day is a testing time for me.

A question is like this in a competitive exam model question paper:

" From a point on ground, a vertical pole of height ' h' is situates away by a distance 'a'. When a ball is thrown at an angle of 45 Deg., the ball just clears the pole height and falls at a distance 'b' on the other side of it. Find the height of the pole. Sketch - I am unable to put here or draw or paste.

The choice of the answers given is as follows. given below.

1. (ab)/(a-b)

2. (ab)/(a+b)

3. (2ab)/(a+b)

4. (ab)/(a +2b)

Now which one among the above 4 choice sis the correct answer.

My Answer is:None of the above is correct answer. The reason is when a ball is thrown at an angle of 45 Deg., the ball will follow a parabolic trajectory and will have maximum range. (Dynamics chapter of Mathematics studied during 2nd year of Engineering Degree.) and fall on the opposite side of the person throwing the ball.

Ignoring friction of air, max range will be 2 times the distance between the pole and the person.

Hence height of the pole denoted as 'h' is equal to "a" the distance between the person and the pole.

Since the angle of throw is 45 Deg., the height of the pole becomes opposite side of the triangle and the distance between the person and pole becomes adjacent side of the triangle.

In the Trigonometry opposite side/adjacent side = tan 45 = 1.

Hence the height of the pole is equal to the distance between the pole and the person. Hence the correct answer is " NONE OF THE ABOVE"

This is the question for a competitive exam for my grand son.

I want to know the views from the CR4 members.

DHAYANANDHAN.S

## Comments rated to be Good Answers:

Re: Mathematics question" by BruceFlorida on 11/04/2017 6:48 AM (score 2)Re: Mathematics question" by Rixter on 11/04/2017 10:22 PM (score 3)Re: Mathematics question" by Dan A on 11/06/2017 5:05 AM (score 2)Re: Mathematics question" by Rixter on 11/06/2017 8:18 AM (score 6)## Comments rated to be "almost" Good Answers:

Re: Mathematics question" by Rixter on 11/04/2017 10:11 AM (score 1)Re: Mathematics question" by jhhassociates on 11/05/2017 7:14 AM (score 1)