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Date May 2021 Marks available 4 Reference code 21M.1.AHL.TZ1.6
Level Additional Higher Level Paper Paper 1 (without calculator) Time zone Time zone 1
Command term Find Question number 6 Adapted from N/A

Question

It is given that cosecθ=32, where π2<θ<3π2. Find the exact value of cotθ.

Markscheme

METHOD 1

attempt to use a right angled triangle        M1

correct placement of all three values and θ seen in the triangle        (A1)

cotθ<0 (since cosecθ>0 puts θ in the second quadrant)        R1

cotθ=-52        A1

Note: Award M1A1R0A0 for cotθ=52 seen as the final answer
         The R1 should be awarded independently for a negative value only given as a final answer.

 

METHOD 2

Attempt to use 1+cot2θ=cosec2θ        M1

1+cot2θ=94

cot2θ=54        (A1)

cotθ=±52

cotθ<0 (since cosecθ>0 puts θ in the second quadrant)        R1

cotθ=-52        A1

Note: Award M1A1R0A0 for cotθ=52 seen as the final answer
         The R1 should be awarded independently for a negative value only given as a final answer.

 

METHOD 3

sinθ=23

attempt to use sin2θ+cos2θ=1        M1

49+cos2θ=1

cos2θ=59        (A1)

cosθ=±53

cosθ<0 (since cosecθ>0 puts θ in the second quadrant)        R1

cosθ=-53

cotθ=-52        A1

 

Note: Award M1A1R0A0 for cotθ=52 seen as the final answer
         The R1 should be awarded independently for a negative value only given as a final answer.

 

[4 marks]

Examiners report

[N/A]

Syllabus sections

Topic 3— Geometry and trigonometry » AHL 3.9—Reciprocal trig ratios and their pythagorean identities. Inverse circular functions
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Topic 3— Geometry and trigonometry

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