Skip to content
MathsGenie logo
Quick links
Open app

Course home

  1. A Level
  3. Maths WJEC
  5. Question bank

3.5 Trigonometry (A-level only)

EasyMediumHard
1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283
Question 8
a.

By writing cos⁡3x \cos 3x\,cos3x as cos⁡(2x+x)\cos(2x + x)cos(2x+x), show that cos⁡3x=4cos⁡3x−3cos⁡x\cos 3x = 4\cos^3 x - 3\cos xcos3x=4cos3x−3cosx.

[2]
b.

Solve, for 0≤x≤1800 \leq x \leq 1800≤x≤180, the equation,

4cos⁡3x−3cos⁡x=−0.65 4\cos^3 x - 3\cos x = -0.65 4cos3x−3cosx=−0.65

Give your answers to 1 decimal place.

[4]

3.5 Trigonometry (A-level only) Questions

  1. A Level
  2. /Maths
  3. /3.5 Trigonometry (A-level only)