00:03
So we have our integral from pi over 3, pi over 2, twice second 2 theta, tan of 2 theta, d theta.
00:49
So we observe readily that since the derivative of secant is secant tan, and that's exactly the format we have here.
00:58
So if we put a substitution of t equaling second 2 theta, then d of t equals second 2 theta times tan of 2 theta times the derivative of twice theta, which is 2, d theta.
01:48
And that's exactly what we have as the integrant over here.
01:52
So this equals integral.
01:57
The whole of two secant 2 theta, 10 of 2 theta becomes, we have here that becomes d of t.
02:06
And now we have to change the limits accordingly because these were the limits for theta...