Inspired by WishBoNe’s recent Bali escapade, Miss Loi decided to take a mini-break of her own and headed to a pristine beach somewhere in the region.
It was postcard-perfect day as she slipped into her sexy bikini, strutted to the waterfront and settled down with a glass of cocktail, oblivious to the lecherous pairs of eyes gawking from a distance.
Whatever postcard serenity was ruined by a sudden cry of “TSUNAMI!“, as Miss Loi looked up to see a distant wall of water hurtling towards her.
As the gawking eyes fled to higher ground, however, Miss Loi began to question the wisdom of abandoning her expensive cocktail mix and fleeing straight into the welcoming company of lecherous cheekopeks on higher ground, clad in a sexy bikini.
With her supernatural trigonometric powers, she managed to deduce the equation of the wave. But time is of the essence, and some questions still needed to be answered …
The wave f is defined, for 0o ≤ x ≤ 180o, by
f(x) = 2cos4x-1
- Solve the equation f(x) = 0.
- State the amplitude of f.
- State the period of f.
- State the maximum and minimum values of f.
- Sketch the graph of y = f(x)
Given that the amplitude is in metres, and that the beach is at f(x) = 0, and that Miss Loi’s around 1.7m tall, and that her primary concern is not to ruin her expensive make-up that comes with UV protection, should she run in order to save her make-up life? If she stayed at the beach, how many ‘peaks’ of the wave would she need to survive, assuming the wave only lasted for the number of cycles within the range of 0o ≤ x ≤ 180o?
Please, there’s no time to lose before the waves come crashing down on the beach! Miss Loi needs you to really know your graphs of trigonometric functions well to answer this quickly!
That’s why she used the word “state” many times in the question, which means there’s no time for any workings for those parts!
P.S. This is a speed question i.e. it’s not about whether you know how to do but how fast you can do this, get your marks, and move on. Do not dwell > 5 mins on a question like this!
Disclaimer: This story is entirely fictitious. There was no tsunami (and they don’t behave according to that equation), no sexy bikini, and most importantly Miss Loi is definitely not 1.7m tall.
