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mathslover Group TitleBest ResponseYou've already chosen the best response.1
Prove : \(\sin (90  \theta) = \cos \theta\)
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
Actually I am confused that how can I : prove that sin in 2nd quadrant is +ve ? That is my basic confusion ...
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
can u use sin (AB) formula?
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
No idea. Actually that was just in start and the formula arises later, so I think that there must be an easier method?
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
draw a right triangle
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
:( not so good but OK ? :)
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
dw:1350046739720:dw nothing is there without naming , OK now I think.
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
dw:1350046691525:dw now find sin 90theta and cos theta using basic defination
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
OK wait please !
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
In case of sin 90  theta , will perpendicular be : adjacent (base) and base will be opposite?
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
know the basic defination of sin and cos ? dw:1350046897401:dw apply it here, in terms of a and b,c
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
OH IT IS soh cah toa and not soa cah toa , sorry :(
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
sin = opposite / hypotenuse cos = adjacent / hypotenuse
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
sin (90theta) = b/c cos (theta) = b/c and hence sin(90theta) = cos(theta) , got it now? lol jk. Well is this right @hartnn
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
yep, hence proved.
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
next identity please.
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
prove that sin in 2nd quadrant is +ve ? That is my basic confusion ...
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
here, put theta = theta
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
and use cos(theta) = cos theta
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
how to prove that cos(theta)=theta ?
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
again with the use of right triangle @hartnn ?
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
how will u find theta in triangle ?
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
oh yes .. silly me . So, a cartesian plane ?
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
no, cartesian plane will not work also.
 2 years ago

sara12345 Group TitleBest ResponseYou've already chosen the best response.1
ccw : +ve angle cw : ve angle
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
because lengths will be positive , so ratio will always come out to be positive, hence, maybe cartesian plane won't work
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
Some how agreed .
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
searched net now, http://www.mathsisfun.com/algebra/trigfourquadrants.html is that the correct one ?
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
yes, its correct....we could prove it using coordinates.... (cos t,sin t)= (x,y) so sin t is +ve in 2nd quadrant
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
doubts ended :) thanks a lo.
 2 years ago

mathslover Group TitleBest ResponseYou've already chosen the best response.1
*ton/lot.
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
mathisfun is always a nice reference....
 2 years ago

sara12345 Group TitleBest ResponseYou've already chosen the best response.1
more we knw more confuse we become
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.8
more we practice, more the confusion vanishes....
 2 years ago

sara12345 Group TitleBest ResponseYou've already chosen the best response.1
more we practice, more ways we look at things n hence more confusions which ofcourse gives kick ;p
 2 years ago
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