+118608 Here is a graph of y=tan(theta)
It illustrates what Geno is telling you :)
https://www.desmos.com/calculator/jsz7qq1cam
ALSO
It is important to remember that $$tan\theta=\frac{sin\theta}{cos\theta}$$
and Cos 270 = 0 Anything divided by 0 is undefined 
+23246 The value of tan(-270°) is undefined.
If you approach this by finding these values:
tan(-269°) = -57.2899...
tan(-269.9°) = -572.957...
tan(-269.99°) = -5729.577...
tan(-269.999°) = -57295.779...
The values have a limit of -∞.
If you approach this by finding these values:
tan(-271°) = 57.2899...
tan(-270.1°) = 572.957...
tan(-270.01°) = 5729.577...
tan(-70.001°) = 57295.779...
The values have a limit of ∞.
So, tan(-270°) doesn't equal either -∞ or ∞.
+118608 Here is a graph of y=tan(theta)
It illustrates what Geno is telling you :)
https://www.desmos.com/calculator/jsz7qq1cam
ALSO
It is important to remember that $$tan\theta=\frac{sin\theta}{cos\theta}$$
and Cos 270 = 0 Anything divided by 0 is undefined
