Find the value of x by using the exterior angle theorem

What basic trigonometric identity would you use to verify that sin x cos x tan x =1-cos^(2)x?

Which ordered pair is a solution to the system of linear equations? 2x + 3y= 6 –3x + 5y = 10

David is spreading mulch on a triangular area of his flower bed. the coordinates of the vertices of the area are (1, 3), (9, 3), and (4, 6). what is the area of the triangle if each square has an area of 3 square feet?