Which solid results from the rotation

Which triangles area would be calculated using the trigonometric area formula

Which is an equation for the nth terms of the sequence 12,15,18,21

He weights of 2-pound bags of best dog food are approximately normally distributed with a given mean  and standard deviation  according to the empirical rule, what percentage of the bags will have weights within 3 standard deviations of the mean? 47.5%68%95%99.7%