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Date May 2022 Marks available 6 Reference code 22M.1.AHL.TZ2.7
Level Additional Higher Level Paper Paper 1 (without calculator) Time zone Time zone 2
Command term Find Question number 7 Adapted from N/A

Question

By using the substitution u=secx or otherwise, find an expression for 0π3secnxtanxdx in terms of n, where n is a non-zero real number.

Markscheme

METHOD 1

u=secxdu=secxtanxdx         (A1)

attempts to express the integral in terms of u         M1

12un-1du         A1

=1nun12  (=1nsecnx0π3)          A1

 

Note: Condone the absence of or incorrect limits up to this point.

 

=2n-1nn         M1

=2n-1n          A1

 

Note: Award M1 for correct substitution of their limits for u into their antiderivative for u (or given limits for x into their antiderivative for x).

 

METHOD 2

secnxtanxdx=secn-1xsecxtanxdx         (A1)

applies integration by inspection         (M1)

=1nsecnx0π3          A2

 

Note: Award A2 if the limits are not stated.

 

=1nsecnπ3-secn0         M1

 

Note: Award M1 for correct substitution into their antiderivative.

 

=2n-1n          A1

  

[6 marks]

Examiners report

[N/A]

Syllabus sections

Topic 3— Geometry and trigonometry » SL 3.5—Unit circle definitions of sin, cos, tan. Exact trig ratios, ambiguous case of sine rule
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