Question

Law of cosines: a2 = b2 + c2 – 2bccos(A)

Which equation correctly uses the law of cosines to solve for y?
92 = y2 + 192 – 2(y)(19)cos(41°)
y2 = 92 + 192 – 2(y)(19)cos(41°)
92 = y2 + 192 – 2(9)(19)cos(41°)
y2 = 92 + 192 – 2(9)(19)cos(41°)

Answer 1

The correct answer is:

D.
`y^(2)=9^(2)+19^(2)-2(9)(19)cos(41)`

`|Huntrw6|`

Answer 2

In this case,
a = y
b = 9
c = 19
So...

`a^2 = b^2 + c^2 - 2bc*\cos(A)`

`y^2 = 9^2 + 19^2 - 2*9*19*\cos(41^(\circ))`
which means the answer is choice D