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You are here: Home / Category Index / Trigonometry / Solving Simple Trigonometry Problems.
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Solving Simple Trigonometry Problems. - By Ryan Sherlock
How to use this applet:You can click and drag on any of the corners of the triangle to reshape it. (To reconstruct past questions)
The Reset button returns the triangle to it's original position.
The Add Line button adds another point to the triangle that can be draged to create more complex problems.
The Scale scroll bar lets you alter the scale of the triangle. Eg. 10 meter side to a 100 meter side.
The Drop Down Menu lets you choose between worked examples of the Cosine and Sine formulae as well as an example of Pythagorases Theorm that appear on the bottom right panel.
The box bellow the buttons gives all angles that are in the trinagle(s).
The white box at the bottom gives all areas of the triangles.
Notes on the maths used in the applet:Steps to solving simple trigonometry problems.
1. Write down everything you know about the triangle, and label all angles with capital letters and the distances opposite with lower case of that letter.
2. Write down the label (Eg. Angle A or distance c) distance/angle that is needed for the answer
3. If there is a right angle in the triangle calculate everything about the triangle that you can using Pythagorases Theroem, and the Triangle Laws.
4. Use the Sine and Cosine formulae to find all other information in the triangle by substituting in values you know in to the formulae, only include one veriable. (Usually the one you need for you answer, but you might have to calculate some other values first before you can use the equations to find your value.)
For example if you know length b, and length c (The lengths opposite Angle B and Angle C), and you have the value for Angle A, you can use the Cosine formula to find the length of a.
EG. b = 10 meters, c = 10 meters, Angle A = 80°
Cosine Formula is
a² = b² + c² - 2bcCosA.
Thus.
a² = (10)² + (10)² - 2(10)(10)Cos(80°)
a² = 200 - 34.7296
a² = 165.27
a = 12.85
Which is correct!
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