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Geometry 9-12 / Week 12 / Wednesday
3/6
Week 12 · Modeling the Set and Opening Night

Wednesday

Shop Lab: the honeycomb panel
// Every prop a shape, every plan a number
⏱ about 20 min

Wednesday: Shop Lab, the Honeycomb Panel

Comet holds a cardboard hexagon against the panel. "Side 10. I measured center to edge: 8.7. Why do these fit so well?"

"Look at a corner where three meet," Wren says. "What do you notice?"

"Three angles, no gap." She checks with the protractor. "Each one is 120. Three of them make 360."

Nova projects three pentagons around one point. A thin wedge of empty space shows. "Would you like a hint? Try 108 three times."

"324. A gap," Comet says. "So pentagons leave holes and hexagons do not. What can we make of the whole panel?"

"We counted 114 tiles on it," Wren says. "Our designer, find a tile's area and check the count."

What you need

  • Cardboard or thick paper, a ruler, a protractor, a pencil and scissors.
  • A sheet of paper or a tray to tile, about the size of a placemat.
  • Your Shop Book.
Safety first
Cut cardboard with scissors only, sitting down, with the points turned away from you. A grown-up cuts thick cardboard.
Keep offcuts in a pile so the floor stays clear. Nothing heavy is moved alone.

Run the lab

  1. Draw a regular hexagon with 5 cm sides: six 60 degree turns of the protractor around a center point.
  2. Cut it out with scissors and use it as a template to cut nine more.
  3. Measure the apothem: from the center straight to the middle of one side. Write it down.
  4. Tile the tray. Put three tiles around one corner and check that no gap shows.
  5. Count how many tiles cover the tray. Measure the tray. Find the tiles per square unit.
  6. Compute one tile's area: six triangles, each half of side times apothem. Multiply by the count and compare with the tray.

The crew's panel data

The crew's own tile: side 10 cm, apothem 8.7 cm as measured. The panel is 2 m by 1.5 m.

MeasureValue
interior angle of a regular hexagon120°
angles meeting at one corner3 × 120° = 360°, no gap
interior angle of a regular pentagon108°, and 3 × 108° leaves a gap
one triangle of the tilehalf of 10 × 8.7 = 43.5 square cm
one tile (six triangles)261 square cm
tiles counted on the panel114
area the tiles cover114 × 261 = 29,754 square cm
area of the panel30,000 square cm

The tiles cover 29,754 square centimeters of a 30,000 square centimeter panel. The small difference is the trimmed edge tiles.

A regular hexagon tiles with no gaps because its interior angle divides 360 exactly. A pentagon's does not.

ANGLES OF THE TILE
  • Read the question.
  • Tap your answer.
What is each interior angle of a regular hexagon tile?
What is each exterior angle of a regular hexagon tile?
What is each interior angle of a regular pentagon?
AREA OF THE TILE
  • Read the question.
  • Tap your answer.
A triangle with base 10 cm and height 8.7 cmOne of the six triangles in the tile has base 10 cm and height 8.7 cm. What is its area in square centimeters?
A tile is six triangles of 43.5 square centimeters each. What is the tile's area in square centimeters?
114 tiles cover the 3 square meter panel. What is the density in tiles per square meter?
What the lab showsTrue or false?
Three regular hexagons meet at a corner with no gap.?
Three regular pentagons meet at a corner with no gap.?
Four squares meet at a corner with no gap.?
The apothem runs from the center to a corner of the hexagon.?
WHY THIS EXERCISEThe angle test tells the crew which tile shapes can cover a panel before any cardboard is cut.
How many degrees do the angles around one corner of the panel add to? Type the number.
WHY THIS EXERCISEA full turn is 360 degrees, which is exactly what three hexagon corners provide.
Draw three hexagons meeting at one corner and three pentagons meeting at one corner. Shade the gap.

Careful tiling, designer. Tomorrow the crew designs under constraints: the least fabric and the most seats.

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