## briana.img one year ago Can someone walk me through this problem? I always have a hard time with this.

1. briana.img

2. briana.img

@EmilyF03 excuse me?

3. briana.img

I tried this but it didn't seem to work for me $8^2=4^2+7^2-2(4)(7)\cos$

4. ganeshie8

$8^2=4^2+7^2-2(4)(7)\cos(\theta)$

5. ganeshie8

isolate $$\cos(\theta)$$ first

6. briana.img

i ended up with -57=cosT but i don't think that's right

7. ganeshie8

you should end up with -1 = -56cos(T) right?

8. ganeshie8

dividing -56 both sides gives you 1/56 = cos(T)

9. briana.img

don't i need to put it in cos^-1(-56) ?

10. jim_thompson5910

cos(T) ? shouldn't it be cos(R) since you want to find m < R ?

11. briana.img

@jim_thompson5910 ooh oops yepp i was just going off an example in my notes

12. jim_thompson5910

ah, gotcha