It is true because if a is perpendicular to b and b is perpendicular to c therefore a has to be perpendicular to c also they said that all three lines are coplanar therefore the statement must be true
I hope this helped you out :)
Answer:
625 cm^2
Step-by-step explanation:
Break it into a rectangle on the bottom and a triangle on top
rectangle area = 50 x 8 = 400 cm^2
triangle area = 1/2 b * h = 1/2 * 50 * 9 = 225 cm^2
added together = 625 cm^2
The GCF of 18 and 39 is 3