Aline parallel to the line 3x+4y+8=0 with y-intercept 4

Find the distance between (7,-6) and (-3,-9)

Scores on the cognitive scale of the bayley-scales of infant and toddler development range from 1 to 19, with a standard deviation of 3. calculate the margin of error in estimating the true mean cognitive scale score, with 99% confidence, if there are 12 infants and toddlers in a sample.

What are the triple angle formulas? is it related to double angle identities?