Yahoo Answers: Answers and Comments for Verify the identity cot(xpi/2)=tan x? [Mathematics]
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From Kim
enUS
Fri, 08 Dec 2017 21:01:56 +0000
3
Yahoo Answers: Answers and Comments for Verify the identity cot(xpi/2)=tan x? [Mathematics]
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https://answers.yahoo.com/question/index?qid=20171208210156AAafDqI
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From Pinkgreen: LHS=
cos(xpi/2)/sin(xpi/2)=
[cos(x)*0+sin(...
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https://answers.yahoo.com/question/index?qid=20171208210156AAafDqI
Fri, 08 Dec 2017 22:04:58 +0000
LHS=
cos(xpi/2)/sin(xpi/2)=
[cos(x)*0+sin(x)*1]/
[sin(x)*0cos(x)*1]=
sin(x)/[cos(x)]=
tan(x)=
RHS.

From cidyah: cot(xpi/2) = cos(xpi/2) /sin(xpi/2)
cos(ab...
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https://answers.yahoo.com/question/index?qid=20171208210156AAafDqI
Fri, 08 Dec 2017 21:33:52 +0000
cot(xpi/2) = cos(xpi/2) /sin(xpi/2)
cos(ab) = cos(a)cos(b) + sin(a)sin(b)
sin(ab) = sin(a)cos(b)  cos(a)sin(b)
cos(xpi/2) = cos(x) cos(pi/2) + sin(x)sin(pi/2)
= cos(x) (0) + sin(x) (1)
= sin(x)
cos(xpi/2) = sin(x)
sin(xpi/2) = sin(x) cos(pi/2)  cos(x) sin(pi/2)
= sin(x) (0)  cos(x) (1)
= cos(x)
sin(xpi/2) = cos(x)
cot(xpi/2) = cos(xpi/2)/sin(xpi/2) = sin(x)/(cos(x)) = tan(x)

From ted s: depends upon what YOU know....cos ( x  π / 2 ...
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https://answers.yahoo.com/question/index?qid=20171208210156AAafDqI
Fri, 08 Dec 2017 21:18:15 +0000
depends upon what YOU know....cos ( x  π / 2 ) = sin x and sin (x  π / 2 ) =  cos x...thus their ratio is  tan x