Find the perimeter of this semi-circle with diameter, d = 39cm. Give your answer rounded to 1 DP.
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Answer:
Step-by-step explanation:
You can create a right triangle out of this information and then use right triangle trig to solve.
We are given the height of the triangle as the height of the tower which is 150m.
We are given the angle of inclination as the degree the tower makes with the ground which is 72.
From the angle of 72 degrees, which is also known as the reference angle, we have the side across from it (the height) and we are looking for the side adjacent to it (how far from the base of the tower the keys will land). Side opposite the reference angle over side adjacent to the reference angle is the tangent ratio:
and, solving for x,
Make sure your calculator is in degree mode to solve this. Divide 150 by the tan(72) and find that
x = 48.7 m