The sun is 21° above the horizon. it makes a 54 m -long shadow of a tall tree. how high is the tree? express your answer in meters.

Can someone explain to me how to do this problem ?

Animals respond in various ways to stimuli detected through their senses. some of these responses are stimulated by the presence of danger. which of these animal responses is the best example of a response to an immediate threat? a) a rooster crows every morning at the first sign of light. b) as something approaches an octopus, it shoots a cloud of ink. c) from late fall until spring, bears hibernate to preserve energy. reactivate d) a dog is getting hot in the sunlight, so he moves to a shaded area.

Which planet do you think would be easiest for humans to colonize some day?