If `("cos"(x-y))/("cos"(x+y))+("cos"(z+t))/(cos(z-t))=0` , then the value of expression `tanxtanytanztant` is equal to (a)`1` (b) `-1` (c)` 2` (d) `-2`

Explanation

To solve the equation

\[ \frac{\cos(x-y)}{\cos(x+y)} + \frac{\cos(z+t)}{\cos(z-t)} = 0, \]

we will manipulate the left-hand side step by step.

...