Question about the Law of Sines?

Question

I vaguely remember something about not using The Law of Sines in conjunction with basic trig. For instance, if I have a polygon that I split up into triangles, and I use The Law of Sines to find a side that happens to be the hypotenuse of a right triangle (as in a non-right-triangle that shares a side with the hypotenuse of a right-triangle), will there be an error if I use basic trig to find the other angles, sides, etc. in the right triangle?

Am I just making this up in my head?

Sorry if this sounds confusing...

Basically, is there any case in which using The law of Sines and normal trig will give you an incorrect answer?

Answer 1

This does indeed sound confusing. The basic definition of sine is as follows:
In a triangle ABC with a right angle at B, then
sin(BAC) = BC / AC (opposite / hypotenuse).

The sine rule is a separate formula, and applies to any triangle. If a is the side opposite angle A, b is the side opposite angle B, and c is the side opposite angle C, then:
a / sin(A) = b / sin(B) = c / sin(C).

Answer 2

If NOT a right angled triangle:
If you have one side and an opposing angle, you can use sine rule. (a/Sine A = b/Sine B = c/Sine C) where 'a' is the length of a side and 'A' is the angle opposing it.

If this does not work you could use the Cosine Rule - a^2=b^2+c^2- 2bc Cosine A where 'a' is the length of a side and 'A' is the angle opposing it.

Hope this helps

Answer 3

no there should not be a problem with what you are trying to do. the law of sines applies to any triangle not just right triangles and it is that sinA/a = sinB/b = sinC/c

Answer 4

I don't know and I thought the law of sines was for any triangle.
You could always draw a scaled drawing and check your work.

Answer 5

check this link its good


http://workathomeandearnmoney.blogspot.com/


.