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Understanding Limas

Limas was waking up the space bounded by a square-n and some triangle whose base coincides with the n-side and meet at a point outside of the pedestal.
Limas Types

The name of a pyramid is determined by the shape of its base. Based on the shape of pyramid base has several names such as the following
1. Limas Segi-three

The picture above is called triangular pyramid T.ABC as a triangular base. Elements owned triangular pyramid T.ABC as follows:

   1. Base field is the field of ABC
   2. Side of the plane upright TAB, TBC, and TAC
   3. Ribs upright namely TA, TB, and TC
   4. Ribs pedestal namely AB, BC, and AC
   5. The peak point of the point T
   6. The high line is a line drawn from a point T and perpendicular plane base ABC.

2. Limas Segi-four

Pictured above is called triangular pyramid T.ABC as a triangular base. Elements owned triangular pyramid T.ABC as follows:

   1. Base field is the field of ABCD
   2. Side of the plane upright TAB, TBC, TCD, and TAD
   3. Ribs upright namely TA, TB, TC and TD
   4. Ribs pedestal namely AB, BC, CD, and DA
   5. The peak point of the point T
   6. The high line is a line drawn from a point T and perpendicular plane base ABCD.

3. Limas Segi-Five

The picture above is called triangular pyramid T.ABC as a triangular base. Elements owned triangular pyramid T.ABC as follows:

   1. Base field is the field of ABCDE
   2. Side of the plane upright TAB, TBC, TCD, TDE, and TAE
   3. Ribs upright namely TA, TB, TC, TD and TE
   4. Ribs pedestal namely AB, BC, CD, DE, and AE
   5. The peak point of the point T
   6. The high line is a line drawn from a point T and perpendicular plane base ABCDE.

4. Limas Segi-n

For the n-side pyramid has elements that

Field side of = n + 1

Vertices = n + 1

Rib = 2 n
Limas formula
1. Volume Limas

To find the volume of the pyramid used the formula:
Limas Volume = 1/3 x area Alas x t
2. Surface

To find the surface area of ​​the pyramid used the formula:
L = Number of Broad fields side.
Example Problem Limas

1. A rectangular pyramid and a square-shaped base volume 1350 cm3. If the pyramid is 18 cm high, specify the length of the base

Completion

Dik: V = 1350 cm3 and height = 18 cm

V = 1/3 x L x t

1350 = 1/3 L. 18th

1350 = 6 L

L = 1350/6 = 225 cm2

Because the base is a square then L = s2

L = 225 cm2

s2 = 225 cm2 = 15 cm

Given a right triangle pyramid S.PQR like the picture above. If the area around the side of the upright is 84 cm2 and 108 cm2 surface area, specify:

   1. The pyramid base area
   2. PR length.

Completion

1. Volume of pyramid = 1/3 × base area × height

60 = 1/3 × base area × 6 cm

3 × 60 = area of ​​the base × 6

area of ​​the base = 180/6

= 30

So, SPQR pyramid base area is 30 cm2.

2. Area of ​​the triangle PQR = ½ × PR × RQ

30 = ½ × 5 × RQ

60 = 5 × RQ

RQ = 60/5

= 12

Thus, the length is 12 cm RQ