The radius is 10.. the radius is half of the diameter
We are seeing 30, 60, 90, triangles, and 45, 45, 90, triangles.
13. 3 root 3
14. 5 root 2
15. 7/2 root 2
16. 3/2 root 2
17. 7.5 root 3
19. bc is squared root 37
20. 32 + 32 root 3
what makes it irrational is the

which does not change from one zero to the other. so if one root its irrational the other one also is. Answer A
The trigonometric values for cos are C = A/H, which means that to find cos(60), you need to divide the adjacent side by the hypotenuse, which in this case gives you 1/2, so that is the value of cos(60).
I hope this helps!
Answer:
1 1/3
Step-by-step explanation: