Help needed with Trigonometry (1 Viewer)

[Sunray]

Hi this is my first post, anyway i am just having some trouble with a Trigonometry Question Any help Would be Appreciated.
Question is in the Image below

 

[deswa1]

For this, when I say O I mean the base of the tower and T is the top of the tower.
(a)- Use trig in triangle OAT
(b)- Use the information you worked out in part a in order to do trig in triangle OBT
(c)- Use Pythagoras in triangle OAB

Good luck

 

[Timske]

for a)
Using a/sinA = b/sinB

h/sin25 = 80/sin65
h = 80sin25/sin65
= 37.3m

 

[deswa1]

for a)
Using a/sinA = b/sinB

h/sin25 = 80/sin65
h = 80sin25/sin65
= 37.3m

It would have been much easier to use sinx=Opposite/hypotenuse giving h=80tan25 straight away

 

[RealiseNothing]

It would have been much easier to use sinx=Opposite/hypotenuse giving h=80tan25 straight away

It isn't a right angle triangle though.

 

[Timske]

it is right angled.

 

[RealiseNothing]

it is right angled.

ok let me re-word it:

It is right angled, but you can't assume that, we only know it's right angled after using the sine rule.

 

[deswa1]

No, you can assume its right angled because since its a tower, by definition it is vertically up. Therefore it is at a perpendicular with the ground, meaning that its a right angle.

 

[Timske]

i didnt assume i knew it was right angled lol

 

[Carrotsticks]

ok let me re-word it:

It is right angled, but you can't assume that, we only know it's right angled after using the sine rule.

You can assume it, as they did not tell us the angle that the tower was leaning.

 

[Sunray]

Thanks for your help guys the reason I had trouble as I was not sure if it was right angled

 

[Caboufram]

http://www.wolframalpha.com/