Answer:
63
Step-by-step explanation:
Tangents drawn from external point to a circle are congruent.
Therefore,
SG = SD
8x - 9 = 5x + 18
8x - 5x = 9 + 18
3x = 27
[tex]x = \frac{27}{3} \\ x = 9 \\ SG = 8x - 9 \\ SG =8 \times 9 - 9\\ SG =72 - 9 \\ \huge \red{ \boxed{SG =63}}[/tex]
