2條 f4 a-maths(subsidiary angle / multiple angle)

Subsidiary angle:

1)Consider the equation k cos -2(cos x + sin x) = √5 ...........(‧)

(a) Show that cos(x + α) = √5/ ( √(k^2 - 4k + 8)) , where tan α = 2/(k-2)

(b) If (‧) has real solution(s) for x, find the ranges of values of k.



Multiple angle:

1)If sin θ = 3/5 and θ is obtuse, find the value of tan θ/2



請清楚列明點計