00:01
Hi, here in this given problem, this is the wall having a ring attached to this wall like this.
00:13
Two forces, force f1 making an angle theta with the horizontal and force f2 making an angle phi with the horizontal.
00:30
The magnitudes of these forces f1 is equal to 30 pounds and f2 is equal to 40 pounds.
00:41
The resultant force is along x axis and that is given as fx is equal to 60 pounds.
00:50
It means there is no net force along y axis.
00:55
So, if we resolve these forces, horizontal component of f1 that is f1 cos theta and its vertical component that is f1 sin theta and horizontal component of f2 that is f2 cos phi and vertical component that is downward.
01:20
So, this is minus f2 sin phi.
01:24
So, this f1 sin theta plus minus f2 sin phi that is equal to 0 or we can say 30 sin theta is equal to 40 sin phi or sin theta is equal to 4 by 3 sin phi or squaring both the sides we get sin square theta is equal to 16 by 9 sin square phi.
02:07
Now, in place of sin square theta we can say this is 1 minus cos square theta that is 16 by 9 sin square phi...