Answer:
70.5°
Step-by-step explanation:
22² = (20)²+(18)² - 2(20)(18) cos X
484 = 400 + 324 - 720 cos X
-240 = -720 cosx
1/3 = cos X
= X
X = 70.52877937
T h e. a n s w e r I s t h r e e
I we consider her running times as an arithmetic series with common difference:
43.13 - 43.1 = -.03/2 = -.015, Shelly's time in the fourth race will be 43.1 - .015 = 43.085.