The curve y = acos bx+c, where a, b and c are integers, passes through the points (-π/6,-2) and (π/2, 1). The curve has a period of 2π/3.
- (a)Find the values of a, b and c.[4]
- (b)Find the least value of y on the curve for 0 ≤ x ≤ π/2, and state the value of x at which this occurs.[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2024). The mark or mark type is shown in brackets.
- [B1] b = 3
- [M1] Use of y = a cosbx + c, with their b and either set of given coordinates
- [A1] c = -2
- [A1] a = 5
- [B1] Minimum when cos bx = −1 soi
- [B1] x = π / 3
- [B1] y = -7
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