Worked Out Answer 3.4 1e from: Maths in Motion – Theo de Haan
For the sake of simplicity, leave out the limits of integration. Rewrite as:
Identify sin (except for a minus sign) as the derivative of cos . You can also identify cos as the derivative of sin , but unfortunately this doesn’t work out quite the same way...
Rewrite as: Substitute: So d becomes: Now substitute u and d
= = cos d = Please note that u (and therefore cos ) has to be greater than zero. =
= = cos d = = By changing over to again, you can use the original limits of integration:
= You have found: The definite integral now becomes: = =0.62 In radians!ln(1) = 0