16 thru 23 look wrong and 16 is absolutely wrong. You use this:https://www.mathpapa.com/algebra-calculator.html to work out the answers and it shows the steps and explains it to you better than I could. Good luck
Answer:
9^2= 81, √25= 5, 21^2= 441, √4= 2, √144= 12, 16^2= 256, √625= 25, (-11)^2=121
7
1.4x10^
Hope this helps!!!!!!!!!
Answer:


Step-by-step explanation:
A) If AB is a diameter, Then ACB is a 90 degrees angle because In a semi-circle (AB is a diameter which divides the circle into 2 equal parts), the angle opposite to the diameter is of 90 degrees.
So, <ACB = 90 degrees
Then <a = 180-90-28
=> <a = 62 degrees
B) The opposite interior angles of a quadrilateral inscribed in a circle add up to 180 degrees.
So,
=> <a + <b = 180
=> <b = 180-62
=> <b = 118 degrees