Eric Nicholas K's answer to LockB's Secondary 3 A Maths Singapore question.
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Q4b, Q4c, Q4d
Date Posted:
3 years ago
for 4b,why cosx=0 gives pi/2 and 3pi/2
These are special results which I have included earlier:
sin x = 0 gives 0, 180, 360
cos x = 0 gives 90, 270
tan x = 0 gives 0, 180, 360
sin x = 0 gives 0, 180, 360
cos x = 0 gives 90, 270
tan x = 0 gives 0, 180, 360
how about the one at 4c sinx=-1 gives 270
The full results
sin x = 0 gives 0, 180, 360
cos x = 0 gives 90, 270
tan x = 0 gives 0, 180, 360
sin x = 1 gives 90 (this can be seen from the graph or usual solving for sin)
cos x = 1 gives 0, 360 (this can be seen from the graph or usual solving for cos)
tan x = 1 gives 45, 225 (this can be seen from the usual solving for tan)
sin x = -1 gives 270 (this can be seen from the graph or usual solving for sin)
cos x = -1 gives 180 (this can be seen from the graph or usual solving for cos)
tan x = -1 gives 135, 315 (this can be seen from the usual solving for tan)
sin x = 0 gives 0, 180, 360
cos x = 0 gives 90, 270
tan x = 0 gives 0, 180, 360
sin x = 1 gives 90 (this can be seen from the graph or usual solving for sin)
cos x = 1 gives 0, 360 (this can be seen from the graph or usual solving for cos)
tan x = 1 gives 45, 225 (this can be seen from the usual solving for tan)
sin x = -1 gives 270 (this can be seen from the graph or usual solving for sin)
cos x = -1 gives 180 (this can be seen from the graph or usual solving for cos)
tan x = -1 gives 135, 315 (this can be seen from the usual solving for tan)
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