00:01
This is not drawn to scale, but this is a quick schematic of the system.
00:05
And we have our knowns on the right.
00:08
So we want to find essentially the resultant of the forces applied to the bracket by members a and b.
00:20
So we have a and we have b.
00:24
So we want to find the resultant force vector.
00:28
So there's two approaches.
00:30
We can use cosine law or the law of signs.
00:34
So first let's just do cosine law.
00:36
So cosine law, in this case we can have r squared equals f a squared plus fb squared plus, rather minus minus 2fa, f sub b, cosine of beta.
01:01
And so this is very straightforward.
01:04
R squared equals 15 squared plus 15 squared minus 2 times 15 times 15 times cosine of 120 degrees.
01:23
And so r squared equals then 675 or we can say r is going to be equal to 25 .98 or approximately 26 kiloons...