Square and Triangle

Geometry Level 2

The above figure is a Triangle of a Triangular Prisms with B C D F BCDF Square attached inside.

Given that Area A B F ABF is 25 25 and A B : B F = 1 : 2 AB : BF = 1 : 2 and the height of the Triangular Prisms is 15 15

Find the surface Area of the Triangular Prisms

Round your answer to zero decimal place.


The answer is 1628.

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1 solution

Jason Chrysoprase
Feb 18, 2016

From the picture above, we can conclude that

Assume that the real A B AB is n n

A B F ABF Area = = A B × B F 2 \frac {AB \times BF }{2}

25 = n × 2 n 2 25 = \frac {n \times 2n}{2}

25 = n 2 25 = n^2

n = 5 n = 5

So A B = 5 AB = 5 and B F = 10 BF = 10 , now move to the next step

From the figure above, we also knew that Triangle A B F ABF is congruent with Triangle A C E ACE , so ;

A B B F = A C C E \frac{ AB}{BF} = \frac { AC }{CE}

5 10 = 15 C E \frac { 5 }{10 } = \frac { 15 } { CE }

C E = 30 CE = 30

Now find the area of the triangle,

15 × 30 2 = 225 \frac { 15 \times 30 }{2} = 225

Now find the Triangular Prisms Surface Area

A C × h + C E × h + A E × h + 2 ( A C E AC \times h + CE \times h + AE \times h + 2 ( ACE Area ) = ) = Surface Area

15 × 15 + 30 × 15 + 1 5 2 + 3 0 2 × 15 + 2 ( 225 ) = 15 \times 15 + 30 \times 15 + \sqrt { 15^2 + 30 ^2 } \times 15 + 2 ( 225 )= Surface Area

1628.115... = 1628. 115 ... = Surface Area

By rounding the answer to zero decimal

1628 = \color{#20A900}{\boxed {1628}} = Surface Area

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