Standing 140 feet from the base of a tree, Alejandro uses his clinometer to site the top of the tree. The reading on his clinometer is 42 degrees. If his eyes are 6 feet above the ground, how tall is the building ?

132 feet

Step-by-step explanation:

Given that Alejandro is standing at a distance of 140 feet from the base of the tree and his eyes are 6 feet above the ground.

Let AB is the height of the tree and point E is the location of his eyes which is 6 feet above from C on the ground as shown in the figure.

The distance between points A and C, AC=140 feet.

Drawing a horizontal line from point E which meets AB at point D as shown.

As ACED forms a rectangle, so

AC=DE=140 feet ...(i)

CE=AD= 6 feet ...(ii)

The height of the tree, AB=AD+DB

By using equation (ii),  AB=6+DB ...(iii)

Now, given that the on watching the top of the tree, the reading on the clinometer is 42 degrees.

So,

In triangle DEB,

[from (i)]

feet

From equation (iii) the height of the tree is

AB=6+126=132 feet.

Hence, the height of the tree is 132 feet.

something that characterises a right triangle is the fact that we may use pythagoras' theorem to find any one of its sides given that we have the length of the other two sides. here, we have the length of the hypotenuse, √(87) yd, and one other side, √(23) yd, thus we can easily find the length of the remaining side using pythagoras' theorem as defined below:

c^2 = a^2 + b^2, where c is the length of the hypotenuse, and a and b are the lengths of the other two sides.

thus, given that c = √(87) and a = √(23), we may substitute these into the formula we defined above to get:

c^2 = a^2 + b^2

(√87)^2 = (√23)^2 + b^2 (substitute c = √87 and a = √23 into the equation)

87 = 23 + b^2 (evaluate (√87)^2 = 87 and (√23)^2 = 23 - remember that the square root of a number, squared will equal that very same number)

64 = b^2 (subtract 23 from both sides)

√64 = b (take the square root of both sides)

8 = b (evaluate √64 = 8)

therefor, the length of the unknown leg in the right triangle is 8 yd (first answer).