Question

Determine a soma dos ângulos internos de um icoságono convexo ?

Answer 1

S n = (n-2).180

S20= (20-2).180

S20= (18). 180

S20= 3240°

Answer 2

$\large\displaystyle\boxed{\begin{array}{l} \sf \: S_i = (n - 2) \cdot180 {}^{ \circ} \\ \\ \sf \: S_i = (20 - 2) \cdot {180}^{ \circ} \\ \\ \sf \: S_i = 18 \cdot180 {}^{ \circ} \\ \\ \boxed{ \boxed{ \sf{S_i = 3240 {}^{ \circ} }}}\end{array}}$