00:01
Hello in this question let us first of all understand what is given.
00:05
Okay, so we are given that this length bc is 12.
00:09
This length ac is 15 and this ab is x and dx over dt is given to us that is one feet per second.
00:21
These our lengths are in fit all.
00:24
Okay.
00:25
So we need to calculate d theta or dt.
00:28
This is angle theta and we need to calculate.
00:31
To calculate d theta or d t when theta is 30 degree okay so we will use the rules of technometry and a differentiation here so we will assume this as h okay so as we know bd over bc it is equal to what sine theta okay so bd will be bc sine theta okay so bd will be c so, when theta is 30 degree, we can calculate value of bd, that would be 12 into sine 30, that would be 1 by 2, so that would be 6.
01:22
So bd at that point would be 6.
01:25
But if you differentiate it on both sides, then d .h over dt, it would be equal to bc that was constant, that was 12, into sine theta, differentiation of sine theta would be cos theta into d.
01:43
So if we get our dh over d t, we can calculate d theta or d t.
01:48
Okay, so for d h over d t, what we will do? and we will calculate this length dc.
01:56
Dc would be what? 12, cos 30, that would be 6 root 3...