Find the reference angle! I NEED HELP ASAP PLS!

What are the measures of ∠a, ∠b, ∠c and ∠d? explain how to find each of the angles. measure need asap

Asquare has a side that measures 11 units. what is the area of a circle with a circumference that equals the perimeter of the square? use 3.14 for π, and round your answer to the nearest hundredth. 1519.76 units2 379.94 units2 616.56 units2 154.14 units2

An investment decreases in value by 30% in the first year and decreases by 40% in the second year. what is the percent decrease in percentage in the investment after two years