Calculate a side in a non-right angled trangle

Elz

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Hi! I'm supposed to calculate one of the sides in a isosceles triangle that is not right angled. Two of the sides are 9cm and I know that one of the angles is Sin(B) = 2/5.
I tried to solve it through "cutting" the triangle in half and then then try to calculate it... But i don't really know what to do after that haha :confused:

(I treid to upload an image of the problem, but apparently i didn't work)

Please help me!!
 
Hi! I'm supposed to calculate one of the sides in a isosceles triangle that is not right angled. Two of the sides are 9cm and I know that one of the angles is Sin(B) = 2/5.
I tried to solve it through "cutting" the triangle in half and then then try to calculate it... But i don't really know what to do after that haha :confused:

(I treid to upload an image of the problem, but apparently i didn't work)

Please help me!!
If the vertices of the triangle are A, B & C,:

Can you describe which sides are 9 cm?

Do you know laws Sines and Cosines for triangles?
 
If the vertices of the triangle are A, B & C,:

Can you describe which sides are 9 cm?

Do you know laws Sines and Cosines for triangles?

I'm familiar with the laws yeah!
likbent-triangel.png

I found a triangle on google to try to explain i better haha.. so ab = 9. And I'm supposed to calculate aa.
 
I'm familiar with the laws yeah!
likbent-triangel.png

I found a triangle on google to try to explain i better haha.. so ab = 9. And I'm supposed to calculate aa.
Use law of Cosines.

If you are still stuck, reply back showing work.
 
Hi! I'm supposed to calculate one of the sides in a isosceles triangle that is not right angled. Two of the sides are 9cm and I know that one of the angles is Sin(B) = 2/5.
I tried to solve it through "cutting" the triangle in half and then then try to calculate it... But i don't really know what to do after that haha :confused:

(I treid to upload an image of the problem, but apparently i didn't work)

Please help me!!

What you did should work; can you show it to us so we can find an error or see where you stopped?

But you haven't quite said yet which angle is B in your problem. Is it the apex labeled "b" in your picture, or is it one of the base angles labeled "a"? If you are given the sine of the apex angle (which your line would cut in half), then the method you describe would require a half-angle formula. And no matter what you do, I think you will need to find cos(B).
 
Hi! I'm supposed to calculate one of the sides in a isosceles triangle that is not right angled. Two of the sides are 9cm and I know that one of the angles is Sin(B) = 2/5.
I tried to solve it through "cutting" the triangle in half and then then try to calculate it... But i don't really know what to do after that haha :confused:

(I treid to upload an image of the problem, but apparently i didn't work)

Please help me!!

you know the sin, so you know an angle.
you know there are 1800 in a triangle.
and that two angles are equal.
and you know 2 sides.
 
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