Find the total area for the pyramid with the equilateral base. • 12 +36v3 sq. units
• 36 + 144V3 sq. units
• 144 +36V3 sq. units
• 36 +12V3 sq units

Option A is the correct answer.

Explanation:

The given pyramid has 3 lateral triangular side as shown below.

Base of triangle = 12 unit

We need to find perpendicular.

 By Pythagoras theorem we have

           Perpendicular² = 10²-6²

          Perpendicular = 8 unit

So area of 1 lateral triangle = 1/2 x Base x Perpendicular.

                                            = 1/2 x 12 x 8 = 48 unit²

Area of lateral side = 3 x 48 = 144 unit²    

Please tell me if im right i believe i am :)

Step-by-step explanation:

Area formula for equilateral triangle with side a:

The base area is:

The three lateral surfaces have same sides of 10, 10 and 12.

Find each surface area using heron's formula:

Total surface area is:

Correct choice is C

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15