The expression can be written:
3((1/sin(x))-1)(tan(x))2,
Let x=π/2-h, then sin(π/2-h)=cos(h) and tan(π/2-h)=cot(h)=1/tan(h).
When h is small, tan(h)=h approx, tan2(h)=h2 approx, and cos(h)=1-h2/2 approx. 1/cos(h)=1+h2/2 approx, so 1/cos(h)-1=h2/2 approx.
The expression approximates to 3(h2/2)/h2=3/2=1.5. As h→0, x→π/2, so the limit is 1.5. Note that it doesn't whether h is positive or negative, h2 is always positive.