For this case we have that by definition:
![Sin (90) = 1\\Cos (90) = 0](https://img.qammunity.org/2020/formulas/mathematics/high-school/7n2fi6x9gnn143w0c3eos4fm97sq3otjid.png)
Now, the tangent of 90 is given by:
![tg (90) = \frac {Sin (90)} {Cos {90}} = \frac {1} {0}](https://img.qammunity.org/2020/formulas/mathematics/high-school/49gqlnvv97jzojmzh1itlw7cmib9ojbxyu.png)
Thus, it is observed that the tangent of 90 degrees is not defined. Is obtained ∞.
Similarly:
![Sin (-90) = - 1\\Cos (-90) = 0](https://img.qammunity.org/2020/formulas/mathematics/high-school/ikf2xv06hutmd358a3scbo2k4hqh9aow7a.png)
Now, the tangent of -90 is given by:
![tg (-90) = \frac {Sin (-90)} {Cos {-90}} = \frac {-1} {0}](https://img.qammunity.org/2020/formulas/mathematics/high-school/2hc3crhgsybm0oma070o40ppvtjkh3ghxw.png)
Thus, it is observed that the tangent of -90 degrees is not defined.
Answer:
False