Formulas HW for algebra. First correct answer gets a heart and 5 stars.

What is the measure of one interior angle of a pentagon

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.

Cos^2x+cos^2(120°+x)+cos^2(120°-x)i need this asap. pls me