00:02
So for the region, under the graph of a certain function, between that and the x -axis, what you actually do is you take the integral, as you may or may not have heard, the integral for the given bounds, so the interval specified 0 to pi over 3 in this case, of the function, but specifically the absolute value of the function.
00:28
If you're just looking at specifically the area, because if we're looking at the area, then what goes under the curve should rather add instead of subtracting from the result.
00:41
So what you need to do then is be able to split this integral into the parts that are positive and the parts that are negative.
00:51
But the thing is, as you may notice, and you should already know how to check this, but basically for the interval from 0 to pi over 3, tan x is, in fact, always positive, and secant x is always positive as well.
01:23
And you can check this using various ways, such as the unit circle or just looking at the graphs.
01:29
But that makes things easier, basically, because then the absolute values can just be removed if they're positive so we'll start with r1 our 1 font r1 is integral from 0 to power 3 of tan x dx and for that you'll need the integral of tan x and by use substitution that would be equal to it would be equal to one of absolute value of c x plus c so basically r1 is going to be equal to you're going to sub the two values the two bounds in.
02:16
You can get long absolute value of secant.
02:18
Sorry, there should have another absolute value on there.
02:21
Sequent pi over three minus long absolute value, secant zero.
02:32
And before i, i'm just going to do the same thing for the next part, the other region.
02:41
And r2 is going to therefore be just equal to the integral of just function since it's always positive anyway and this is a known integral that you may have been asked to prove before so i won't show that here but the integral is equal to the it's equal to the law of absolute value of secant x plus tan x so here i'm just going to draw a line to split down split up the work basically r2 is going to be equal to one has the value secant pi 3.
03:31
So yeah, we're going to first sub in pi over 3 because that's the upper bound plus 10 by over 3 and then subtract and we're going to sub the lower bound 0.
03:43
So we have minus the lineups value so you can 0 plus 10 0.
03:49
Now for each of these regions we're just going to have to sub the different values in.
03:55
Really what we just need to know, we can just write them all down...