rewrite the following biconditional statement into conditional statement (if-then form)

16. A shape is rectangle if and only if it has four sides.
if-then form:

17. A triangle is equilateral if and only if it is equiangular.
if-then form:

18. An angle is a right angle if and only if it has a measure is 900.
if-then form:

19. Two angles have the same measure if and only if the angles are congruent.
if-then form:

20. Three lines are coplanar if and only if they lie in the same plane.
if-then form:​