Tim Gan Math
Sign up free

Trigonometric ratios of related angles written in terms of a given cosine of an acute angle

Trigonometric ratios of related angles written in terms of a given cosine of an acute angle

IB Year 6 | Grade 12
9 marks

It is given that \(\cos25^\circ=k\). Without using a calculator, find an expression in terms of \(k\) for each value below.

  1. \(\sin25^\circ\)[1]
  2. \(\cos50^\circ\)[1]
  3. \(\cos155^\circ\)[1]
  4. \(\sin205^\circ\)[1]
  5. \(\cos335^\circ\)[1]
  6. \(\tan205^\circ\)[1]
  7. \(\sin65^\circ\)[1]
  8. \(\cos115^\circ\)[1]
  9. \(\tan245^\circ\)[1]

Solution:

Solution locked

680+ questions here come with free worked solutions. A free account saves your questions and progress; this one needs tuition enrolment.

Create free accountSign inIB Math tuition

Create a free account to practise similar questions.

Create free accountSign inIB Math tuition
Answer:(a) \(\sqrt{1-k^2}\) (b) \(2k^2-1\) (c) \(-k\) (d) \(-\sqrt{1-k^2}\) (e) \(k\) (f) \(\dfrac{\sqrt{1-k^2}}{k}\) (g) \(k\) (h) \(-\sqrt{1-k^2}\) (i) \(\dfrac{k}{\sqrt{1-k^2}}\)

Need help? Join our JC Math tuition classes.

Learn more