please answer and show work:

Question 21 (1 point) Find the area of the triangle with the following vertices. A[1, 1, -1). 8(2. 0. 1),and C[1. -1, 2) O 10 Oo O25 O V5 Question 22 (1 point) John makes it to work on time one Monday out of four. On other work days his behavior is as follows: If he is late one day, he is twice as likely to come to work on time the next day as to be late. If he is on time one day. he is as likely to be late as not the next day. Find the probability of his being late on Wednesdays. O O O 16 O 16