Sides & angles of a triangle using sine?

Question

How can I use sine to figure out the 2 missing sides of a triangle if I know one length? And the angles too?

Answer 1

If you know at least two angles, then you can find the third angle by subtracting both from 180 degrees.

If you know one side and all the angles, then you can use the Law of Sines formula to find all the remaining sides.

Check the link for the formula and a picture of a triangle so you can see how to set this up.

Answer 2

Let me remind you what the sine rule is:

Let A, B and C be the vertices of a triangle ABC. Let the sides opposite these vertices be a, b and c respectively. Then,

a/Sin A = b/Sin B = c/Sin C = 2r

Where r is the radius of the circumcircle of triangle ABC.

I guess you could find out what everything is if you were given the length of a side, the measure of r and the measure of two angles. Or, you could also compute the rest if a side and all the angles were given. One side alone is not enough.

Don't think that my answer can be the only correct one. Others can also be right. I'm not as good in trigonometry or geometry for that matter, as I am at algebra and number systems.

Answer 3

The law of sines is A/sinA = B/sinB = C/sinC, where side A is opposite angle A, etc. So this formula works if you know one side and 2 angles.

Answer 4

Let's say you have your triangle ABC.
You know angles A, B and C.
And you know side 'a'.

Your unknowns are side 'b' and side 'c'.

The sine rule is : a / sinA = b / sinB = c / sinC.

Start with a / sinA = b / sinB.
Multiplying through by sinB gives : b = asinB / sinA
You know all these values, so you can now find 'b'.

Next, you can use : a / sinA = c / sinC.
Multiplying through by sinC gives : c = asinC / sinA.
You know all these values too, so you can now find 'c'.

Answer 5

it's quite simple

i can't draw a triangle here but
................................. /i-this angle is 34 degree
............................. c / i
.............................. / .ib
......this is 56 degree /_ i
............................... a=5cm

Sin degree=oppsite side/adjacent side
so in this case it would be sin 34 degree= 5/c theres the first side
the second side you can use tangent formula to solve it which is opposite side/adjacent side=a/c
Tan 34 degree = 5/b

that is as best i could have explain it hope it helps!!
heh heh and drawing a triange is hard on here

Answer 6

I forgot, but I remember they were trigonemetric ratios, and You need to use this formula i forgot using the lengths of the sides....