+57 Side a=16, side b=6, and side c=17.1
I figured out that angle A is 20.6, but when I try to find the next angle (angle B) I always come just a few decimal points off
What am I doing wrong
this is what I did
Cos(A)=6/17.1
Cos(A)=0.350877193
Cos⁻¹0.350877193=69.45902246
69.45902246-->69.5
My teacher says that the answer is 69.3
So could you tell me why I am off by so little
+129899 Law of Cosines
6^2 = 16^2 + 17.1^2 - 2 [ 16 * 17.1] cos B rearrange as
[ 6^2 - 16^2 - 17.1^2 ] / [ -2 * 16 * 17.1 ] = cos B
Take the cosine inverse
arccos ( [ 6^2 - 16^2 - 17.1^2 ] / [ -2 * 16 * 17.1 ] ) = B ≈ 20.54°
Likewise
[ 16^2 -6^2 - 17.1^2 ] / [ -2 * 6 * 17.1 ] = cos A
arccos ( [ 16^2 -6^2 - 17.1^2 ] / [ -2 * 6 * 17.1 ] ) = A ≈ 69.34°
