View Full Version : Precal using angles
sdlinsey
Apr 26, 2009, 02:13 PM
A building 150 feet tall casts a 50 foot long shadow. If a person stands at the end of the shadow and looks up to the top of the building, what is the angle of the person's eyes to the top of the building (to the nearest hundredth
Of a degree)? (Assume the person's eyes are 6 feet above ground level.)
Perito
Apr 26, 2009, 02:27 PM
Same problem as the previous one, right?
Tan(\Theta) = \frac {(length\,of\,side\,opposite)} {(length\,of\,side\, adjacent)}
The only difference is that you're six feet above the ground. So, draw a diagram. Note that you can subtract 6 feet from the 150 feet to get the length of the side opposite.
sdlinsey
Apr 26, 2009, 02:38 PM
Same problem as the previous one, right?
Tan(\Theta) = \frac {(length\,of\,side\,opposite)} {(length\,of\,side\, adjacent)}
The only difference is that you're six feet above the ground. So, draw a diagram. Note that you can subtract 6 feet from the 150 feet to get the length of the side opposite.
OK i drew the diagram
Perito
Apr 26, 2009, 02:42 PM
What did you get for Theta?
Tan(\theta)=\frac {150-6}{50} = \frac {144}{50} = 2.88
sdlinsey
Apr 26, 2009, 02:47 PM
What did you get for Theta?
Tan(\theta)=\frac {150-6}{50} = \frac {144}{50} = 2.88
I got 2.88 but this is where I'm getting confused
Perito
Apr 26, 2009, 02:51 PM
If
tan(\theta) = 2.88
you use the "arctan" function (angle whose tangent is) to get the result.
ArcTan (or arctan) is the same as tan^(-1)
\theta = tan^{-1}(tan(\theta)) = tan^{-1}(2.88) = 70.85\,degrees
I'm not sure how you get values for your arctan function, but it exists on most scientific calculators.
sdlinsey
Apr 26, 2009, 02:56 PM
If
tan(\theta) = 2.88
you use the "arctan" function (angle whose tangent is) to get the result.
ArcTan (or arctan) is the same as tan^(-1)
\theta = tan^{-1}(tan(\theta)) = tan^{-1}(2.88) = 70.85\,degrees
I'm not sure how you get values for your arctan function, but it exists on most scientific calculators.
o OK i forgot all about arctan thank you