Step-by-step explanation:
we have a right-angled triangle, that is "hovering" 1.61 m above the ground.
the Hypotenuse (the side opposite of the 90 degree angle) is the line of sight from the eye to the top of the skyscraper.
one leg is the height of the skyscraper (minus the 1.61 m).
the other leg is the ground distance from Jacob to the skyscraper (281 m).
we know already 2 angles : the 90° angle between the ground distance and the skyscraper height. and the 25° between the ground distance and the line of sight.
and as we know that the sum of all angles in a triangle is always 180°, we know that the third angle (between the line of sight and the skyscraper height) is
180 - 90 - 25 = 65°
now we can use the law of sines
a/sin(A) = b/sin(B) = c/sin(C)
(the ratio between a side and its opposing angle)
to get all missing side lengths.
the 25° angle is opposite of the skyscraper height, and the 65° angle is opposite of the ground distance (the only side length we know so far).
so,
height/sin(25) = 281/sin(65)
height = 281 × sin(25)/sin(65) = 131.0324519... m
to get the full height of the skyscraper, we need to add the 1.61 m that the described triangle was "hovering" above ground.
therefore, the height of the skyscraper is
131.0324519... + 1.61 = 132.6424519... ≈ 132.6 m
or
<-- there's no plus/minus sign.
<-- root.
<-- root.
<-- don't forget to distribute the negative.