For each <em>x</em> in the interval 0 ≤ <em>x</em> ≤ 5, the shell at that point has
• radius = 5 - <em>x</em>, which is the distance from <em>x</em> to <em>x</em> = 5
• height = <em>x</em> ² + 2
• thickness = d<em>x</em>
and hence contributes a volume of 2<em>π</em> (5 - <em>x</em>) (<em>x</em> ² + 2) d<em>x</em>.
Taking infinitely many of these shells and summing their volumes (i.e. integrating) gives the volume of the region:
Answer:
88.7°
Step-by-step explanation:
First, visualize. Assuming that the tower is at a perfectly 90° angle to the ground, you have a right triangle. We will call this triangle ΔABC where A is where you are, B is the top of the tower, and C is the base of the tower. Now we know the following:
∠A = ?
∠B = ?
∠C = 90
a = 346346
b = 7777
c = ?
Note: Triangles are labeled with three pairs of letters: a, b and c and A, B and C. The lower case letters, a, b and c represent the sides, and the upper case letters are the angles that are directly opposite of those sides. (see attached reference)
c is easy, c is the hypotenuse, so you can use the following equation to find the hypotenuse:
a² + b² = c²
Rearranged:
c = ±
Substitute a and b:
c = ±
Comes out to ~346433.3 meters.
Now if we use the Law of Sines:
=
=
We can use c and a, since we're trying to find what angle A is, so the ratio is set up as:
=
Well we know that C = 90, and so sin(90) in degrees (as opposed to radians) is 1. So then the set of equations is now:
=
Cross Multiply to get rid of the fractions:
346346 = 346433.3 * sin(A)
Divide:
= sin(A)
Using a calculator, if you take the arcsin of that fraction, you will get what angle A is supposed to be:
arcsin( ) = ∠A = 88.7°
