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# somehow made 0=undefined Watch

1. it seems like a rather trivial situation but i was just a bit curious...

a c4 question involved subbing in pi/2 into cotx...i put it into cos/sin and got 0, but my friend did it by putting 1/tan(pi/2) into calculator giving undefined...

and i know if you simplify tan to sin/cos it works, its just i cant get past the fact that they SHOULD be equal no matter what form...shouldnt they?! am i wrong in saying cos/sin not just equal to, but identical to, 1/tanx?

thanks for any ideas...
2. (Original post by Tedward)
it seems like a rather trivial situation but i was just a bit curious...

a c4 question involved subbing in pi/2 into cotx...i put it into cos/sin and got 0, but my friend did it by putting 1/tan(pi/2) into calculator giving undefined...

and i know if you simplify tan to sin/cos it works, its just i cant get past the fact that they SHOULD be equal no matter what form...shouldnt they?! am i wrong in saying cos/sin not just equal to, but identical to, 1/tanx?

thanks for any ideas...
The problem there is that tan tends to infinity, and is "undefined" cot tends to 0. The reason being is that is 0. Consider 1/100000000000000000000000 A tiny number now as the denominator gets bigger, the number gets smaller.
3. (Original post by joostan)
The problem there is that tan tends to infinity, and is "undefined" cot tends to 0. The reason being is that is 0. Consider 1/100000000000000000000000 A tiny number now as the denominator gets bigger, the number gets smaller.
sweet that makes sense, thanks!
4. (Original post by Tedward)
it seems like a rather trivial situation but i was just a bit curious...

a c4 question involved subbing in pi/2 into cotx...i put it into cos/sin and got 0, but my friend did it by putting 1/tan(pi/2) into calculator giving undefined...

and i know if you simplify tan to sin/cos it works, its just i cant get past the fact that they SHOULD be equal no matter what form...shouldnt they?! am i wrong in saying cos/sin not just equal to, but identical to, 1/tanx?

thanks for any ideas...
It's because is undefined so if you define cotx as 1/tanx then you'll get cotx to be undefined. But is well defined because

If you consider that then
5. (Original post by Tedward)
sweet that makes sense, thanks!
good
6. (Original post by Felix Felicis)
It's because is undefined so if you define cotx as 1/tanx then you'll get cotx to be undefined. But is well defined because

If you consider that then
Thanks!

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