Indirect Measurement with Trig

All three trig functions are give fraction answers.

Sine = opposite/hypotenuse

Cosine = adjacent/hypotenuse

Tangent = opposite/adjacent

Sine = OPP/HYP

Sin(A) = 21/35

Tangent = OPP/ADJ

Tan(C) = 28/21

You don't ever do a trig function from the right angle

We want to calculate a side when we have a reference angle to work with.

You need a right triangle

And one side and one angle

To find the height of the building, we use tangent

We want to know the height (opposite) and we already know the ground distance (adjacent)

O & A are tangent's letters

​Call the opposite side, the height of the building, x

​Tangent is opposite over adjacent -- what we want, and what we know -- so pick tangent

tan(55) = x/57

1.428 = x/57 [calculator tan(57)]

81.396 = x [mult. both sides by 57]

The height of the building is 81.396​