What is (a) the lateral area and (b) the total surface area of a regular square pyramid with the length of each edge equal to 6? ( leave answers in simplest radical form )

• lateral area: 36√3 square units

• total surface area: (36 +36√3) square units

Step-by-step explanation:

The area of an equilateral triangle of side length s is given by ...

A = (√3)/4·s^2

Your pyramid has four (4) such faces of side length 6 units, so the total (lateral) area of the triangular faces is ...

LA = √3·(6 units)^2 = 36√3 square units

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Of course the area of the square base is simply the square of its edge length, so is ...

A = (6 units)^2 = 36 square units

That means the total surface area, the lateral area plus the base area, is ...

(36 +36√3) square units

starting with:    

5 + x - 12 = 2x - 7   

5 + x - 12 - x = 2x - 7 - x (subtract x from both sides)   

5 - 12 = x - 7 (combine and cancel x's from both sides)   

5 - 12 + 7 = x - 7 + 7 (add 7 to both sides)   

0 = x (add numbers together on both sides)       

so in order for the equation to be true, x must be 0.   

trying x = -0.5   

5 + x - 12 = 2x - 7 (original equation)   

5 + -0.5 - 12 = 2(-0.5) - 7 (plug in value of x)   

5 + -0.5 - 12 = -1 - 7 (did multiplication)   

-7.5 = -8 (did addition on both sides)       

since -7.5 is obviously not equal to -8, the value of -0.5 for x is wrong.   

trying x = 0   

5 + x - 12 = 2x - 7 (original equation)   

5 + 0 - 12 = 2(0) - 7 (plug in value of x)   

5 + 0 - 12 = 0 - 7 (did multiplication)   

-7 = -7 (did addition on both sides)       

since -7 equals -7, that demonstrates that the value of 0 for x is correct.   

trying x = 1   

5 + x - 12 = 2x - 7 (original equation)   

5 + 1 - 12 = 2(1) - 7 (plug in value of x)   

5 + 1 - 12 = 2 - 7 (did multiplication)   

-6 = -5 (did addition on both sides)       

since -6 is obviously not equal to -5, the value of 1 for x is wrong.

answer: x=60