00:01
Let's discuss this question so we need to determine the force in members b e and ca of the loaded trust and the force are positive with the tension and negative within the compression.
00:11
So here let's start.
00:13
Here we can say as we all know b c is equal to c d.
00:19
So in triangle a b d as you can see in the diagram above we use cosine rule.
00:29
So here cos a is equal to ab square plus ad square minus bd square divided by 2 ab multiplied by b multiplied by d.
00:49
That is 2ab multiplied by bd.
00:52
Directly we can say this.
00:54
So here we have cos 50 degrees.
00:57
So cos 50 degree will be equal to 3 .5 square plus 5 .2 square plus 5 .2 square.
01:04
Minus bd square divided by 2 multiplied by 3 .5 multiplied by 3 .5 multiplied by 3 .5 .2.
01:16
So here minus bd square will be equal to 23 .39 minus 12 .25 minus 27 .04.
01:28
So therefore bd is equal to 3 .98 meter.
01:35
This is the final answer so further we can say bc is equal to cd is equal to bd divided by 2 that is equal to 1 .99 meter and here we also need to use the sign rule so here we can say using the sign rule here sign 50 divided by bd will be equal to sine theta divided by ab.
02:24
So here theta will be equal to sine inverse sine 50 multiplied by 3 .5 divided by 3 .98.
02:38
So here we can say theta is equal to 42 .35 degree.
02:47
Here we got the value of theta.
02:50
So further here we can say so here using static equilibrium equation ra plus rb is equal to 3 .1 plus 4 .6 that is equal to 7 .7 km.
03:29
So here we can say on summing moment at a...
