1
3
4
5
B.
3
tan 1
D.
is equalsI_{2} > I_{1}
I_{1} > I_{2}
I_{3} = I_{4}
I_{3} > I_{4}
B.
I_{1} > I_{2}
A man is walking towards a vertical pillar in a straight path, at a uniform speed. At a certain point A on the path, he observes that the angle of elevation of the top of the pillar is 30^{o}. After walking for 10 minutes from A in the same direction, at a point B, he observes that the angle of elevation of the top of the pillar is 60^{o}. Then the time taken (in minutes) by him, from B to reach the pillar, is:
6
10
20
5
D.
5
According to given information, we have the following figure:
Now, from ΔACD and ΔBCD, we have
∵ speed is uniform.
∵ distance y will be cover in 5 min
∵ distance x covered in 10 min
∵ Distance x/2 will be cover in 5 min
A person standing on the bank of a river observes that the angle of elevation of the top of a tree on the opposite bank of the river is 60^{o} and when he retires 40 meters away from the tree the angle of elevation becomes 30^{o}. The breadth of the river is
20 m
30 m
40 m
60 m
A.
20 m