Answer/Step-by-step explanation:
15. Based on the intersecting Chords Theorem, thus,


Divide both sides by 8
x = 15
17. Based on the two secants intersecting theorem,

Solve for c


Subtract 169 from each side

Divide both sides by 13
c = 13.2 (nearest tenth)
19. ✔️Based on the two secants intersecting theorem,

Solve for x


Subtract 25 from each side

Divide both sides by 5
x = 25.8
✔️according to the tangent and secant theorem, thus:

Solve for y


Square both sides
y = 12.4 (nearest tenth)