Question

36.
A bird is sitting on the top of a 80m high tree. From a point on the ground the angle on
elevation of the bird is 45°. The bird fly away horizontally in such a way that it remained a
a constant height from the ground. After 2 seconds the angle of elevation of the bird fron
the same point is 30°. Find the speed of flying of the bird.​

Answer 1

Answer:

40(root 3 - 1) m/s

Step-by-step explanation:

tan 45 = 80 / x so x = 80

tan 30 = 80 / y so y = 80 root 3

distance covered in 2 seconds

= 80 root 3 - 80 = 80(root 3 - 1)

speed = distance / time

= 80(root3 - 1) / 2

= 40(root 3 - 1)

Answer 2

Answer:

tan45=BC/ab

BC=ab

ab=80

tan30=od/oa

oa= od√3

ob+ab=80√3

ob+80=80√3

ob=80(√3-1)

speed=80(√3-1)/2

speed=40(√3-1).

=40(0.73)

=29.2m/s