Which formula gives the standard deviation of a data set

Two streets intersect at a 30- degree angle. at the intersection, the are four crosswalks formed that are the same length. what type of quadrilateral is formed by the crosswalks?

Will mark name all segments skew to bc

If the equation of a line containing the midsegment of a triangle is y = -1/4x -11, what is the slope of the triangle side that is opposite the midsegment (the one not touching it). explain how you know.