F fatlord New member Joined Jun 30, 2008 Messages 12 Jun 30, 2008 #1 Lim x -> 0 cot2x / cscx I'm getting cos(2x)/sin(2x) / (1/sin(x)) i'm having trouble reducing after that. help me out
Lim x -> 0 cot2x / cscx I'm getting cos(2x)/sin(2x) / (1/sin(x)) i'm having trouble reducing after that. help me out
G galactus Super Moderator Staff member Joined Sep 28, 2005 Messages 7,203 Jun 30, 2008 #2 \(\displaystyle \lim_{x\to 0}\frac{cot(2x)}{csc(x)}\) \(\displaystyle \frac{cot(2x)}{csc(x)}=\frac{cos(2x)}{sin(2x)}\cdot sin(x)=\frac{cos(2x)sin(x)}{2sin(x)cos(x)}=\frac{cos(2x)}{2cos(x)}\) You can rewrite as \(\displaystyle \lim_{x\to 0}\frac{cos(2x)}{2cos(x)}\) Now, can you see the limit?. Just plug in x=0
\(\displaystyle \lim_{x\to 0}\frac{cot(2x)}{csc(x)}\) \(\displaystyle \frac{cot(2x)}{csc(x)}=\frac{cos(2x)}{sin(2x)}\cdot sin(x)=\frac{cos(2x)sin(x)}{2sin(x)cos(x)}=\frac{cos(2x)}{2cos(x)}\) You can rewrite as \(\displaystyle \lim_{x\to 0}\frac{cos(2x)}{2cos(x)}\) Now, can you see the limit?. Just plug in x=0