Pa answer nga po tnx

2 posts / 0 new
Last post
Hermesable
Pa answer nga po tnx

The angle of elevation of the tower from A is 25°. From another point B, the angle of elevation of the top of the tower is 56°. AB=300m and on the same horizontal plane as the foot of the tower. The horizontal angle subtended by A and B at the foot of the tower is 70°.

What is the height of the tower?
How far A from the tower?
How far B from the tower?

Jhun Vert
Jhun Vert's picture

$x = h / \tan 25^\circ$

$y = h / \tan 56^\circ$
 

trigo-3d-tower.jpg

 

$300^2 = x^2 + y^2 - 2xy \cos 70^\circ$

$300^2 = \left( \dfrac{h}{\tan 25^\circ} \right)^2 + \left( \dfrac{h}{\tan 56^\circ} \right)^2 - 2\left( \dfrac{h}{\tan 25^\circ} \right)\left( \dfrac{h}{\tan 56^\circ} \right) \cos 70^\circ$

$h = 148.8 ~ \text{m}$

Add new comment

Deafult Input

  • Allowed HTML tags: <img> <em> <strong> <cite> <code> <ul> <ol> <li> <dl> <dt> <dd> <sub> <sup> <blockquote> <ins> <del> <div>
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
  • Mathematics inside the configured delimiters is rendered by MathJax. The default math delimiters are $$...$$ and \[...\] for displayed mathematics, and $...$ and \(...\) for in-line mathematics.

Plain text

  • No HTML tags allowed.
  • Lines and paragraphs break automatically.