The radius of a circular box is 21 centimeters. what is the circumference of the box? a 66cm b 132cm c 176cm d 1386cm

With these 5 geometry questions! pls 1.)quadrilateral abcd is inscribed in this circle. what is the measure of ∠a ? enter your answer in the box.°2.)quadrilateral abcd is inscribed in a circle. what is the measure of angle a? enter your answer in the box. m∠a= 3.)quadrilateral abcd is inscribed in this circle. what is the measure of angle b? enter your answer in the box. m∠b= °4.)quadrilateral abcd is inscribed in this circle. what is the measure of angle a? enter your answer in the box.°5.) quadrilateral abcd is inscribed in this circle. what is the measure of angle c? enter your answer in the box.°

What is the difference between –12 and –5? what is the distance between –12 and –7 on a number line? units

Me because i don't understand how to do it.: )