Edexcel Further Pure Maths IGCSE (2017) SAM Paper 1 Q10

Monstrous 15 mark question on trigonometry.
The method is too long to adequately list here, but:
-Make heavy use of the pythagorean theorem
-Use the cosine rule to determine an angle in a triangle for which all three sides are known
-Use the "add more dimensions" method to find the distance between two points in the 3D coordinate space

This question is mainly relevant to:
Topic 10 : Trigonometry

[thirunayandinesh]

Can u tell which app are u using to write on the pdf files?

[thelamps]

may i ask how did the 6 for RS come out for part d?