Question
A boat is being rowed away from a cliff 270 m high. From
the top of the cliff, the angle of depression of the boat changes from 60° to 45° in 2 minutes. What is the speed of the boat?Solution
According to the figure above: tan 45° = 270/(a + b) ⇒ 1 = 270/(a + b) ⇒ a + b = 270 Also, tan 60° = 270/a ⇒ √ 3 = 270/a ⇒ a = 270/ √ 3 ⇒ a = 90√ 3 = 155.8 ∴ b = 270 - 155.8 = 114.2 ⇒ The boat covers a distance of 114.2 m in 2 minutes. ∴ Speed of the boat = (114.2 x 60)/(2 x 1000) km/h = 3.4 km/h
Lichens, the pioneer organisms that initiate ecological succession are actually a symbiotic association of
Which one of the following is variety of triticale
‘The law of limiting factors’ was proposed by
In rust cycle, wheat is infected by which of the following spores?
Winter wheat is grown in
Movement of leaves of sensitive plant, Mimosa pudica are due to
Damping off and leaf blights are very effectively checked by
Seed plot technique of potato is used to produce
Breeder is having tag color of
Application developed by Indian institute of wheat and barley research for pest management in wheat crop is