Wednesday

April 1, 2015

April 1, 2015

Posted by **sheila** on Sunday, January 23, 2011 at 5:42am.

- pyramid -
**MathMate**, Sunday, January 23, 2011 at 8:36amIt's similar to the previous question.

Start with drawing a diagram if the book did not supply one.

O is the vertex of the pyramid.

Let D be the centre of the rectangle PQRS, and A=centre of side PQ.

OAD is a right triangle where OD is the height=h, and OA is the height of the slant face OPQ.

By Pythagoras theorem, we find

OA²=sqrt(OD²+AD²)

=sqrt(h²+3.5²)

Area of one slant face

=AQ*OA

=3.5sqrt(h²+3.5²)

Area of 4 slant faces

=14sqrt(h²+3.5²)

Area of rectangular base

=7*7

=49

Equate the sum of areas to total surface area

14sqrt(h²+3.5²)+49=161

Solve for h. I get 7.2 approx.

**Answer this Question**

**Related Questions**

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

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

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

MATH! PLEASE REPLY ASAP! - VWXYZ is a rectangle-based pyramid where WX=66 cm ...

geometry - 1. What is the lateral surface area of a square pyramid with side ...

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

geometry - The surface area of the following square pyramid is 152 cm2. What is ...

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

math - The base of a regular pyramid is a square whose sides have a length 8 cm...

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