Complete the left-hand column of the table below following the steps indicated in the right-hand column to show that sin a sin b=1/2[cos(a-b)-cos(a+b)] is an identity. use the definitions of sum and difference formulas for cosine.

Need on this one asap im almost done with this subject

Martha has a deck of cards. she has lost some of the cards, and now the deck only contains nine spades, eleven diamonds, eight clubs, and twelve hearts. martha predicts that whenever she draws a card from the deck without looking, she will draw a club one-fifth of the time. which activity would best allow martha to test her prediction? a. randomly draw a card from the box and see if it is a club. b. randomly draw a card. then, continue to draw another card until all eight clubs are drawn. c. randomly draw and replace a card 120 times. then, observe how close to 30 times a club is drawn. d. randomly draw and replace a card 100 times. then, observe how close to 20 times a club is drawn.

Are the corresponding angles congruent? explain why or why not.