Because it tends to infinity. Additionally, tangent can be expressed as sin theta divided by cos theta. The sine of 90 is 1. The cosine of 90 is 0. That would be 1 divided by 0, or division by zero; which is undefined.
Cos 90=0 because cos@=base/hyp and at 90degree base becomes zero since zero divided by anything is zero. RPHK_Haider...
90
20 . 2+0 = 2 20 divided by 2 makes 10. Is the same for 30,40,50,60,70,80 and 90.
45 divided into 90 = 0.5
800 divided 90 = 8.88888888888889
90 divided by 5 is 18.
90
2.7778
0.0435
90
0.8182