9709/MayJune/13/2010/Q3

The function f : x  → a + b cos x is defined for 0 ≤ x ≤ 2pi. Given that f(0) = 10 and that f(2/3 pi) = 1, find
(i) the values of a and b, [2]
(ii) the range of f, [1]
(iii) the exact value of f(5/6  pi).  [2]

Solution:
i)

ii)

iii)

Reference: PYQ - May/June 2010 Paper 13 Q3