MCQ
If $\tan (x + y) + \tan (x - y) = 1,$ then ${{dy} \over {dx}} = $
- A${{{{\sec }^2}(x + y) + {{\sec }^2}(x - y)} \over {{{\sec }^2}(x + y) - {{\sec }^2}(x - y)}}$
- ✓${{{{\sec }^2}(x + y) + {{\sec }^2}(x - y)} \over {{{\sec }^2}(x - y) - {{\sec }^2}(x + y)}}$
- C${{{{\sec }^2}(x + y) - {{\sec }^2}(x - y)} \over {{{\sec }^2}(x + y) + {{\sec }^2}(x - y)}}$
- DNone of these