Can someone help me on these and Merry Christmas!

Suppose a man is heterozygous for heterochromia, an autosomal dominant disorder which causes two different‑colored eyes in an individual, produced 25‑offspring with his normal‑eyed wife. of their children, 15 were heterochromatic and 10 were‑normal. calculate the chi‑square value for this observation.

When only separate discreet points are graphed it is called?

When you find the area of a triangle do you use in. or in2