The side of an equilateral triangle is 9 cm. What is the radius of the circle circumscribing this equilateral triangle?
Answer & explanation
Correct answer: option 4
Formula to be used
Circumradius = \(\frac{a \;×\; b \;×\; c}{4 \;×\; area}\)
Calculations
Circumradius = \(\frac{9 \;×\; 9 \;×\; 9}{4 \;×\; √3/4 \;×\; 9 \;×\; 9 }\)
⇒ \(\frac{9}{√3}\) = 3√3 cm
Therefore, the correct answer is 3√3 cm.