Prove tan(θ / 2) = sin θ / (1 + cos θ) for θ in quadrant 1 .

Select all the correct answers. what is 221,000,000,000,000,000,000 expressed in scientific notation?

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%

Write an equation of the line that passes through the point (2, 3) and is perpendicular to the line x = -1. a) y = 1 b) y = 3 c) y = 0 eliminate d) y = -3