We can use two different methods to find our missing angle:
Subtract the two known angles from 180° :
Plug the two angles into the formula and use algebra: a + b + c = 180°
Add 0.5 to each side so you have fabric for the seams and your new numbers are 3 ft and 4 ft
find the area by multiplying 3*4 and get 12 ft
1 yard = 3 feet
12/3= 4 yards
You would need 4 square yards of fabric
57.2-6.7-6.7=43.8
43.8÷6=7.3
7.3×2+6.7=21.3
length = 21.3cm
width = 7.3cm
(21.3×2)+(7.3×2) = 57.2
hope that helps
