Help with this trig word problem!

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• July 26th 2010, 03:17 PM
orkdork
Help with this trig word problem!
Two wires stretch from the top T of a vertical pole to points B and C on the ground, where C is 10 m closer to the base of the pole, than is B. If wire BT makes an angle of 35 degrees with the horizontal and wire CT makes an angle of 50 degrees with the horizontal, how high is the pole?

I know the answer is about 16.98 meters. Please help if you know :D
• July 26th 2010, 04:19 PM
Archie Meade
Quote:

Originally Posted by orkdork
Two wires stretch from the top T of a vertical pole to points B and C on the ground, where C is 10 m closer to the base of the pole, than is B. If wire BT makes an angle of 35 degrees with the horizontal and wire CT makes an angle of 50 degrees with the horizontal, how high is the pole?

I know the answer is about 16.98 meters. Please help if you know :D

Use tangent.

If the distance from the base of the pole to C is x,
then the distance to B is x+10...

h=pole height.

$tan(50^o)=\frac{h}{x}\ \Rightarrow\ h=xtan50^o$

$tan(35^0)=\frac{h}{x+10}\ \Rightarrow\ h=(x+10)tan35^o$

That's two equations for h which must be equal..

$xtan50=xtan35+10tan35$

$xtan50-xtan35=10tan35$

Now factor the LHS and finish.
Once you have x, you can find h.