tirrivee:

askmemathsquestions:

tirrivee:

And help me figure through why it’s wrong. Because it is wrong. I have no idea how, though. 

This is my work through it. All I was given were the values in red, aka C = 52 degrees, a = 51, and b = 17.

Pleeease okay thank.

I can help,but it is not legible, can you post a clear pic?

Hopefully this is better? Thank you!

buddy, it is not wrong, 

it is just a part of sin that we( yes, I also overlooked it and ended up wondering that why it is wrong) overlooked.

It got to me when I was thinking that the sum of two sides of a triangle is always greater than the third side.

so the sides satisfied the criteria, I checked it.

the problem was with angles.

then I thought that sin (180-x) = sin x

so one of the angles that we calculated was actually not the answer, we needed to find 180 - x of that angle because sine rule which was used for calculation of the angles dosen’t tells us if the angle we calculated is x or 180-x

because sin x = sin (180-x)

meaning that we could work out 60 degrees, but the angle could have  been 120 degrees.

so which angle was the culprit here?

All we know is that sine rule is mathematical representation of 

the side opposite to the greater angle is the greatest

so, it had to be angle A, which we calculated as 70.28

it is actually, (180-70.28 )

you get this angle, 

and then when you add up angle C and Angle B, you will get 180 degrees

confirm by cosine rule that (180-70.28) is the correct angle A

And thanks for putting this up, I have a exam tomorow and I just got reminded not to blindly mark the answer once we get it, we should check the validity of our results too

see, how just a tiny detail overlooked and WE ended up wondering why the angles won’t add up.

Thanks for putting this up, you really don’t know, you have just helped me for my exam tomorrow