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OPQRS is a regular square-pyramid whose base has sides of 7 cm. Given that the total surface area of the pyramid is 161 cm2, find its slant height.

• pyramid -

It'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
=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.

Se the methos
H^2= B^2+P^2

You people are just desyroying the math. be ashame ofvyourself you cannot give correct answer of even 1 question shame on yourself

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