How do you calculate the square root of a number without a calculator?

1. ∠1 is complementary to ∠2 and ∠3 is complementary to ∠2. subtraction property of equality 2. m∠1 + m∠2 = 90 and m∠3 + m∠2 = 90 substitution 3. m∠1 + m∠2 = m∠3 + m∠2 definition of complementary 4. m∠1 = m∠3 given

Which equation is represented by the graph below?

The interior angles formed by the sides of a hexagon have measures that sum to 720°. what is the measure of angle a? enter your answer in the box. m∠a= °