Your Turn Find the surface area of each regular pyramid 1 10 2 6 cm 18 cm EXPLAIN 1B Finding the Surface Area of a Pyramid Read the section below and complete the following activity adapted from Lesson 19 3 If only the height altitude of a square pyramid is given one can use the Pythagorean theorem to determine the slant height The slant height of the square pyramid is the hypotenuse of the right triangle formed by the height and half the base length Recall the Pythagorean theorem formula which tells us that the relationship between the legs and the hypotenuse of every right triangle is a b c where a and b are the legs and c is the hypotenuse Finding the Surface Area of a Regular Pyramid if the slant area is not given Step 1 Find the slant height if it is not given Step 2 Find the lateral area RO Altitute Slant height