Somebody please help with these multi-step equation(s)

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

Sarah used her calculator to find sin 125 degrees. she wrote down sin sin125 degrees.57. how could sarah recognize that her answer is incorrect?

List x1, x2, x3, x4 where xi is the midpoint endpoint of the five equal intervals used to estimate the area under the curve of f(x) between x = 0 and x = 10.