The perimeter of an object is found by adding all of the sides. The sides of his frame would be 2 ft, 2 ft, 1.5 ft (18 inches / 12 inches per foot = 1.5 feet), 1.5 feet. Adding these together we get a total length of 7 feet. However, he may want to use a slightly longer board to account for any errors!
If m1 and m2 are the slopes of each line, for them to be perpendicular you gotta solve
m1 * m2 = -1
You may have have forgotten to find the measure of A. Which would by using your 6 that you got would be 19.
16X-6=90
96=16X
X=6
8X6-29
48-29
19
Is it a multiple choice question