Let's see here... the answer is C just by using common sense. A doesn't make sense because you can't cube .4, as it is a percentage, and you wouldn't add that to 1000. B makes no sense because the percentage you are using is 4%, not 30%. Of course, just be sure to fact-check me there.
The first option is your answer.
Sigma notation is just a fancy way to shorten a sum of a series of numbers using a set equation. The "n =" tells you where to start in the sequence and the top number tells you where to stop.
∠BCD = 57°
∴ ∠BDR = ∠BCD = 57° (angle that meets the chord and the tangent is equi-angular to the angle at the alternate segment)
Look at the pictures it explains the equation step by step tell me if you have any questions the answer is at the bottom
