- A396
- B36
- C324
- D78
Step-by-Step Solution
Sheet = . Square removed = . Left . Adding instead of subtracting gives 396; 36 is only the piece cut away, and 78 cm is the sheet's perimeter, not an area.
Answer: C) 324
From a rectangular cardboard sheet 24 cm by 15 cm, a square of side 6 cm is cut away at one corner. Find the area of cardboard that is left (in ).
Class 7Perimeter and AreaPerimeter and Area
Key idea: Parallelogram area
**Area of a parallelogram = base × height.**
Same idea as a rectangle, but the height is the perpendicular distance between the two parallel sides — NOT the slant length of the side. Pick any side as the base, drop a perpendicular to the opposite parallel side, measure that — that's the height.
Example: parallelogram with base 8 cm and perpendicular height 5 cm. Area = . The slant side could be longer; doesn't matter for area.
Perimeter of a parallelogram = 2 × (one side + adjacent side).
Same idea as a rectangle, but the height is the perpendicular distance between the two parallel sides — NOT the slant length of the side. Pick any side as the base, drop a perpendicular to the opposite parallel side, measure that — that's the height.
Example: parallelogram with base 8 cm and perpendicular height 5 cm. Area = . The slant side could be longer; doesn't matter for area.
Perimeter of a parallelogram = 2 × (one side + adjacent side).
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