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Go to this page to see the diagram.

http://i21.tinypic.com/2cqyzab.gif

Thanks!

2007-10-06 15:34:40 · 3 answers · asked by sillyboys_trucksare4girls 2 in Science & Mathematics Mathematics

3 answers

let x be the horizonal distance that form 30 degrees
let h be the height of the building

tan(theta) = opposite / adjacent

tan(20) = h / (45 + x)
tan(30) = h/x

solve for h
h = tan(20) (45 + x)
h = tan(30)x

tan(20) (45 + x) = tan(30)x
tan(20)45 + tan(20)x = tan(30)x
tan(20)45 = tan(30)x - tan(20)x
tan(20)45 = x [ tan(30) - tan(20)]
x = tan(20)45 / [ tan(30) - tan(20)]
x =~ 76.75

tan(30) = h/(76.75)
h =~ 44.31m <== answer

hope this helps

2007-10-06 15:43:41 · answer #1 · answered by      7 · 1 0

First, recognize that the tangent of an angle is equal to the ratio of the opposite side divided by the adjacent side.

We are going to call y the height and x the distance of the 30 degree angle side:
tan of 30 = y/x
tan of 20 = y/(x+45)

Solve for y in the first equation:
(tan of 30)*x = y

Substitute in for y in the second equation:
tan of 20 = (tan of 30)x / (x +45)

Simplify and solve for x:
(tan of 20)(x+45) = (tan of 30)x
(tan of 20)x - (tan of 30)x = -(tan of 20)45
.364x - .577x = 16.38
-.213x = 16.38
x = 76.76

Now we know that x is 76.76 meters.

So to find the height, use the 30 degree triangle.

tan 30 = y/76.76
tan 30* 76.76 = y
y = 44.32

Good luck!

2007-10-06 22:53:01 · answer #2 · answered by tsully87 3 · 0 0

the guys at top are on top of this question, but if it is hard to remember.........I learned sine cosine and tangent like this

sally can tell oscar has a hat on always

sally = oscar/has
can = a/hat
tell= on/always

s = o/h
c= a/h
t = o/a

o isopposite
a is adjacent
h is height

2007-10-06 23:13:51 · answer #3 · answered by Anonymous · 0 0

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