Worked solution
Use a double-angle identity and an exponential substitution
Find
(i) . marks
(ii) , using the substitution . marks
[2013/MI/I/8(i),(iii)]
CJC · Review Problems · Question 2
Answer
(i) ; (ii) .
(i)
Use the source double-angle guidance: . Therefore the integral is .
How did this part go?
(ii)
With , . The integral becomes . Substitute back: . The absolute-value bars match the key; the argument is actually positive.
How did this part go?
Common mistakes
The added constant 2 in an indefinite antiderivative can be absorbed into C, but is retained to match the printed form.