SOME COMMON SENSE FORMULAS
IF YOU KNOW TWO SIDES
And you want to know an angle.
* If you know the legs only use the inverse tangent.
Examples:
tan
-1
(Lleg ÷ Sleg) = Langle
tan
-1
(Sleg ÷ Lleg) = Sangle
* If you know a leg and the hypotenuse use either inverse sine
(sin
-1
) or inverse cosine (cos
-1
) depending on what angle you want.
Examples:
sin
-1
(Sleg ÷ Hyp) = Sangle
sin
-1
(Lleg ÷ Hyp) = Langle
cos
-1
(Sleg ÷ Hyp) = Langle
cos
-1
(Lleg ÷ Hyp) = Sangle
Never divide the Hypotenuse by a leg. (Hyp leg)! It gives a wrong
ratio for our use.
IF YOU KNOW AN ANGLE AND A SIDE
And you want to know another side.
* If you know a leg and an angle and want to know the other leg
always use tangent.
Examples:
tan(Sangle) x Lleg = Sleg
tan(Langle) x Sleg = Lleg
Note the ratios: tan(Sangle) is always less than one, So when you
multiply it times the larger leg it will give you something
shorter. tan(Langle) is always greater than one. When you multiply
it times the smaller leg you will get something longer.
* If you know a leg and an angle and want to know the hypotenuse
divide the legs by sine or cosine of an angle.
Examples:
Sleg ÷ sin(Sangle) = Hyp
Sleg ÷ cos(Langle) = Hyp
Lleg ÷ sin(Langle) = Hyp
Lleg ÷ cos(Sangle) = Hyp
* If you know the hypotenuse and an angle use either Sine or
Cosine.
Examples:
sin(Sangle) x Hyp = Sleg
sin(Langle) x Hyp = Lleg
cos(Sangle) x Hyp = Lleg
cos(Langle) x Hyp = Sleg
Notice how the sine or cosine of an angle is always less than one.
Remember ratio. The legs are always smaller than the hypotenuse.
This number must be less than one so that when you multiply it
times the hypotenuse you will always get something shorter than the
hypotenuse.
Please Donate if
you find this site
helpful.
Thank-You!
No part of this publication may be reproduced, or transmitted, or stored, in any form or by any means, electronic,
mechanical, photocopying, recording, or otherwise, without the prior written permission of SheetMetalWorkBook.com, Sixth
Edition Reformatted for Internet, ©2012 SheetMetalWorkBook.com