How to find the lengths of the two equal sides of an isosceles triangle, when given the base length?

Look at attachment. has all info needed. need

Identify the converse of the following conditional: if a point is in the first quadrant, then its coordinates are positive. if the coordinates of a point are not positive, then the point is not in the first quadrant. if the coordinates of a point are positive, then the point is in the first quadrant. if a point is in the first quadrant, then its coordinates are positive. if a point is not in the first quadrant, then the coordinates of the point are not positive.

What is the reflection image of (5,-3) across the line y = -x?