SOLUTION: Hi, I can't solve this word problem involving right triangles: "A surveyor finds that from point A on the ground the angle of elevation to the top of a mountain is 23degrees. Wh

Algebra ->  Trigonometry-basics -> SOLUTION: Hi, I can't solve this word problem involving right triangles: "A surveyor finds that from point A on the ground the angle of elevation to the top of a mountain is 23degrees. Wh      Log On


   



Question 611188: Hi, I can't solve this word problem involving right triangles:
"A surveyor finds that from point A on the ground the angle of elevation to the top of a mountain is 23degrees. When he is at point B that is 1/4 mile closer to the base of the mountain, the angle of elevation is 43degrees. Assuming that the two points are on the same line, how high is the mountain?"
I don't know how to go about this problem, so if you could, please show and explain the steps as well. I would really appreciate it and it will help me keep up with our lessons. Thank you!

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
You are being asked to compare 2 right triangles, both
of which have a side in common, which is the height.
At the surveyor's 1st position, call his distance from
the base of the mountain +d+ miles
Call the height of the mountain +h+ miles
-------------
(1) +tan%28+23+%29+=+h%2Fd+
and
(2) +tan%28+43+%29+=+h%2F%28+d+-+.25+%29+
------------------------
On my calculator,
+tan%28+23+%29+=+.42447+
+tan%28+43+%29+=+.93252+
--------------------
(1) +.42447+=+h%2Fd+
(1) +h+=+.42447d+
and
(2) +.93252+=+h%2F%28+d+-+.25+%29+
(2) +h+=+.93252d+-+.233130+
--------------------------
Substitute (1) into (2)
(2) +.42447d+=+.93252d+-+.233130+
(2) +.93252d+-+.42447d+=+.233130+
(2) +.50805d+=+.233130+
(2) +d+=+.45887+
and, since
(1) +h+=+.42447d+
(1) +h+=+.42447%2A.45887+
(1) +h+=+.19478+
The mountain is +.19478+ miles high, or
+.19478%2A5280+=+1028.42+ ft high
check answer:
(1) +h+=+.42447d+
(1) +.19478+=+.42447%2A.45887+
(1) +.19478+=+.19478+
OK
(2) +.93252+=+h%2F%28+d+-+.25+%29+
(2) +.93252+=+.19478%2F%28+.45887+-+.25+%29+
(2) +.93252+=+.19478%2F.20887+
(2) +.93252+=+.93254+
Error is due to rounding off