Any want want to help :3 pls

Suppose i flip two identical coins. what is the probability that i get one head and one tail?

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Circle d circumscribes abc and abe. which statements about the triangles are true? statement i: the perpendicular bisectors of abc intersect at the same point as those of abe. statement ii: the distance from c to d is the same as the distance from d to e. statement iii: bisects cde. statement iv: the angle bisectors of abc intersect at the same point as those of abe. a. i only b. i and ii c. ii and iv d. i and iii e. iii and iv