kozy
Find all solutions in the interval [0, 2π).
cos x = sin x
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cwrw238
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divide both sides by cos x to give
tan x = 1
kozy
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okay got that
cwrw238
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the tangent is positive in the first and 3rd quadrants
kozy
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so that gives me pi/4, 7pi/4?
cwrw238
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pi/4 is correct
cwrw238
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kozy
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I have two options with pi/4.. they are 7pi/4 or 5pi/4
cwrw238
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5pi/4 is correct
cwrw238
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pi/4 is in third quadrant
RadEn
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alternative :
cosx =sinx
cosx = cos(90-x)
cosx = cos(k*360 + 90-x)
x = k*360 + 90-x
2x = k*360 + 90
x = k*180 + 45
for k=0, ---> x = 45 degrees
for k=1, ---> x = 225 degrees
convert all x to units pi radian, just divides by 180