Gringo123
Apr2-10, 11:41 AM
I got this question wrong and I'm hoping someone can explain to me where I went wrong.
In a triangle...
angle A = 350
side b = 7 cm
side c = 3 cm
I need to find side a which is the side opposite angle A.
The formaula to use is -a2 = b2 + c2 - 2bc cos A
so, with the figures plugged in that comes out as...
a2 = 72 + 32 - 2 x 3 x 7 cos 35
which comes to...
a2 = 58 - 42 cos 35
SO FAR, I KNOW THAT IS CORRECT. I seem to have made the mistake at this point. I multiplied 16 (58-42) by cos 35 and took the square root of the answer, which gave me 3.62 cm.
However, apparently the right answer is 4.86 cm.
What did I do wrong?
In a triangle...
angle A = 350
side b = 7 cm
side c = 3 cm
I need to find side a which is the side opposite angle A.
The formaula to use is -a2 = b2 + c2 - 2bc cos A
so, with the figures plugged in that comes out as...
a2 = 72 + 32 - 2 x 3 x 7 cos 35
which comes to...
a2 = 58 - 42 cos 35
SO FAR, I KNOW THAT IS CORRECT. I seem to have made the mistake at this point. I multiplied 16 (58-42) by cos 35 and took the square root of the answer, which gave me 3.62 cm.
However, apparently the right answer is 4.86 cm.
What did I do wrong?