Hello!
The answer is: True.
Why?
A counterexample is a way that we can prove that something is not true about a mathematical expression or equation, it could be considered as an exception to a rule, so to check if the answer is true or false, we must prove that a counterexample of the given expression is 0°, so:
The given expression is:
![sinytany=cosy](https://img.qammunity.org/2020/formulas/mathematics/high-school/bs3l8mdl6fjou06dj8jhdck5nsfqep6xk7.png)
Then,
![sin(0)*(sin(0))/(cos(0))=cos(0)\\\\0*(0)/(1)=1\\\\0*0=1\\0=1](https://img.qammunity.org/2020/formulas/mathematics/high-school/rk0kbzqw6gfe160p5en88311uz107vnoen.png)
We can see that the equation is not fulfilled, so 0° is a counterexample of
and the answer is true.
Have a nice day!