Saturday

August 30, 2014

August 30, 2014

Posted by **stressed girl** on Monday, July 8, 2013 at 5:22am.

- Maths -
**Elena**, Monday, July 8, 2013 at 5:57amh=sqrt{H²-(a/2)²} =

=sqrt{15²-6²} = 13.75 cm,

V=ha²/3 =13.75•12²/3=660 cm³,

S= 4•(ha/2) =2•15•12 =360 cm².

- Maths -
**Jai**, Monday, July 8, 2013 at 6:22amSince we cannot draw the figure here, you can draw the figure yourself.

Note that a right pyramid is a pyramid with a square base and the apex (the tip of the pyramid) is aligned directly at the center of the base.

Now, draw an line from the apex to the center of the base, which serves as the height of the pyramid. Then connect the center of the base to one of the midpoints of the side of the square. The slant height is from that midpoint to the apex.

Note that you have formed a right triangle, where the height is unknown, and the hypotenuse (which is also the slant height) is 15 cm. You can solve for the base of the right triangle by getting the half of the side of the square, which is 6 cm.

Solving for height, recall pythagorean theorem. For any right triangle,

a^2 + b^2 = c^2

where

a = base of right triangle

b = height of right triangle

c = hypotenuse

Substituting,

6^2 + b^2 = 15^2

36 + b^2 = 225

b^2 = 189

b = 3*sqrt(21) cm [height]

Recall that the volume of ANY pyramid is just

V = (Area of the base)*(height)/3

*Area of the base = (length of side of square)^2

V = (12^2)*[3*sqrt(21)]/3

V = 144*sqrt(21) cm^3

Recall that the SA of a SQUARE pyramid is just

SA = 2bs + b^2

where

s = slant height

b = length of side of square

SA = 2*12*15 + 12^2

SA = 504 cm^2

Hope this helps~ :)

**Related Questions**

Maths - OPQRS is a right pyramid whose base is a square of sides 12cm each. ...

Mathematics - OPQRS is a right pyramid whose base is a square of sides 12cm each...

MATH! PLEASE REPLY ASAP! - OPQRS is a regular square-pyramid whose base has ...

Maths - Solve the equation:a right pyramid with vertical height stand on ...

Math (check) - what is the slant height for the given pyramid to the nearest ...

geometry - The base of a pyramid is a square. The perimeter of the base is 20ft...

Math - VWXYZ is a rectangle-based pyramid where WX = 66 cm and XY = 32 cm. The ...

Math Homework - 1) Given the side of a square pyramid is 6cm and the altitude is...

math/geometry - What are the surface areas of this two figures? a) a triangular ...

math - Find the lateral area of a regular pyramid whose base is a square whose ...