Geometry primer heavy on application, light on theory

[William Adams]

It's been a long while since geometry in high school.

Ayone got a primer which focuses on "the number solution of this problem is calculated using this formula"?

All I really need is a nicely labeled right triangle w/ all the formulas for the distances and angles marked on it.

Searched, but no luck.

[Alan Rutherford]

Searching Google using your words "labeled right triangle w/ all the formulas" (without the quotes) got me a lot of results in a hurry. Do that and then click on the "images" link. If it's not there, it doesn't exist.

[Alan Caro]

Williams Adams,

For every calculation /conversion problem there is an online calculator. For your query have a look at :

Right Triangle Angle And Side Calculator

> For that you enter two known quantities and it calculates all the angles and lengths of the unknown quantities.

The calculator for triangles with use trigonometry. Right triangles are simpler as the right angle is 90 degree, the sum of the other two angles has to be 90 degrees, and the length of the sides is always a 3:4:5 ratio.

To find this I entered in the Google search window: "how to calculate the angles and lengths right triangle". I often just googlize a calculator with a simple phrase: currency or imperial / metric, slopes in rise / run to angle and percentage, probability/proportional tables, and so on, and there are always dozens of little programs (actually there were 1,090,000 results) that pop up to do it.

Alan Caro

[William Adams]

Thanks!

Managed to find: http://passyworldofmathematics.com/I...077x749JPG.JPG which is close enough to my needs that I'll be abl to draw up a reference sheet from that.

[John K Jordan]

All I really need is a nicely labeled right triangle w/ all the formulas for the distances and angles marked on it.

I could draw one, but... Do you have some specific type of solutions in mind or do you really want a diagram with "all the formulas"? For a right triangle you have five variables: the two non-90 deg angles, the two sides, and the hypotenuse. Most solutions require knowing two things or sometime just one (given one angle, the other is 90 deg minus that angle.) I didn't make a list of all the possibilities of all the other calculations but it might make for a confusing diagram if you included everything. For example, an angle could be determined from the lengths of any two of the three side or from the opposite angle, the hypotenuse could be calculated given the other two sides or from either side and one of the angles. Some solutions simply use the Pythagorean theorum while those involving angles are better done with some trig. However, the exact trig formula to use depends on which angles and sides are provided. I've never thought about this, but a single "do all" diagram might be a mess! Maybe several diagrams?

As someone mentioned, there are a lot of online resources if all you want is to solve a given triangle. Here is one that looks better than many:
http://www.mathportal.org/calculator...calculator.php
Once you provide the required inputs, most will just solve and give you a number, but on this one if you check "Show me an explanation" it will give you the formulas and show you how to solve them. And the answers preserve any square roots instead of simply giving you a decimal number! An equation could be written for each possibility but as mentioned for clarity your labeled diagram might best be several diagrams.

Note: I am certainly no mathematician but I can usually figure out what I need. It gets a little harder with age but I usually just remember a few basic formulas and derive the others as needed. Even that could be a chore if a little rusty on the trig!

JKJ