BQ #5: Unit T Concept 1-3: Graphing sine, cosine, cosecant, secant, tangent and cotangent

Sine and cosine do not have asymptotes, meanwhile all the other trig functions have asymptotes. But, why? Remember that an asymptote forms when there is an undefined ratio/fraction. This means that there is a number divided by 0.
This is based on the trig function's ratios. Sine and cosine have ratios of y/r and x/r. "r" always equals to one in the unit circle so we can be sure that the ratio will never be undefined.
Meanwhile, the ratios for all the other trig functions have a denominator, not of r=1, but of either y or x values, which could happen to be values of 0.