1. You must apply the following formula:
LA=1/2 ×(Perimeter of the base)(Slant length)
2. The slant length is (By the Pythagorean Theorem):
a^2=b^2+c^2
a= b^2+c^2
a=√(1^2+3^2)
a=√10
3. The perimeter of the base is:
P=2+2+2+2
P=8
4. Then, you have:
LA=1/2 ×(Perimeter of the base)(Slant Length)
LA=1/2 ×(8)(√10)
LA=(8√10)/2
LA=4√10