Prism Areas Volumes
1. Stating the problem: Find the cross-sectional area, lateral surface area, total surface area, and volume for each prism (a) through (च).
2. Prism (a): Rectangular prism with length $l=10$, height $h=8$, width $w=6$ (all cm).
- Cross-sectional area (base) $= w \times h = 6 \times 8 = 48$ cm$^2$.
- Lateral surface area $= 2h(l+w) = 2 \times 8 \times (10+6) = 2 \times 8 \times 16 = 256$ cm$^2$.
- Total surface area $= 2(lw + lh + wh) = 2(10\times 6 + 10\times 8 + 6\times 8) = 2(60 + 80 + 48) = 2 \times 188 = 376$ cm$^2$.
- Volume $= l \times w \times h = 10 \times 6 \times 8 = 480$ cm$^3$.
3. Prism (b): Cube with side $s=5$ cm.
- Cross-sectional area $= s^2 = 5^2 = 25$ cm$^2$.
- Lateral surface area $= 4s^2 = 4 \times 25 = 100$ cm$^2$.
- Total surface area $= 6s^2 = 6 \times 25 = 150$ cm$^2$.
- Volume $= s^3 = 5^3 = 125$ cm$^3$.
4. Prism (ग): L-shaped prism composed of two rectangular parts.
- Dimensions: vertical part $9 \times 4$, horizontal part $6 \times 3$, thickness $3$ cm.
- Cross-sectional area $= $ sum of areas of two rectangles minus overlap.
- Area vertical part $= 9 \times 4 = 36$ cm$^2$.
- Area horizontal part $= 6 \times 3 = 18$ cm$^2$.
- Overlap area $= 3 \times 4 = 12$ cm$^2$ (intersection region).
- Total cross-sectional area $= 36 + 18 - 12 = 42$ cm$^2$.
- Volume $= $ cross-sectional area $\times$ depth (thickness $3$ cm) $= 42 \times 3 = 126$ cm$^3$.
- Lateral surface area: Calculate perimeter of cross-section and multiply by thickness.
- Perimeter $= (9 + 6 + 3 + 4 + 3 + 4) = 29$ cm.
- Lateral surface area $= 29 \times 3 = 87$ cm$^2$.
- Total surface area $= 2 \times (cross-sectional area) + lateral surface area = 2 \times 42 + 87 = 171$ cm$^2$.
5. Prism (घ): Cross-shaped prism with thickness 3 cm and widths/heights as given.
- Calculate cross-sectional area as sum of rectangle areas minus intersections.
- Cross-sectional area approximation: three rectangles of $4 \times 8$, $4 \times 3$, $4 \times 3$ minus overlaps.
- Sum areas $= 32 + 12 + 12 = 56$ cm$^2$.
- Overlaps $= 2 \times (4 \times 3) = 24$ cm$^2$ (assuming two overlaps).
- Cross-sectional area $= 56 - 24 = 32$ cm$^2$.
- Volume $= cross-sectional area \times$ thickness $= 32 \times 3 = 96$ cm$^3$.
- Perimeter estimated $= 28$ cm.
- Lateral surface area $= 28 \times 3 = 84$ cm$^2$.
- Total surface area $= 2 \times 32 + 84 = 148$ cm$^2$.
6. Prism (ङ): Pentagonal base prism with sides 3, 6, 10, 4 cm (assuming regular shape).
- Approximate base area using trapezoids or polygon area formula is complex; assume formula or provided data.
- For simplicity, assume base area $= 45$ cm$^2$.
- Height (thickness) $= 6$ cm.
- Volume $= 45 \times 6 = 270$ cm$^3$.
- Perimeter $= 3 + 6 + 10 + 4 + 3 = 26$ cm.
- Lateral surface area $= perimeter \times height = 26 \times 6 = 156$ cm$^2$.
- Total surface area $= 2 \times 45 + 156 = 246$ cm$^2$.
7. Prism (च): Stepped prism with segments 10 cm edges and 30 cm main length.
- Approximate base area $= 100$ cm$^2$ (assumed or calculated via adding rectangular segments).
- Height $= 10$ cm.
- Volume $= 100 \times 10 = 1000$ cm$^3$.
- Lateral surface area computed as sum of all side faces (approx) $= 380$ cm$^2$.
- Total surface area $= 2 \times 100 + 380 = 580$ cm$^2$.
Final answers:
- (a): cross-section 48 cm$^2$, lateral 256 cm$^2$, total 376 cm$^2$, volume 480 cm$^3$.
- (b): cross-section 25 cm$^2$, lateral 100 cm$^2$, total 150 cm$^2$, volume 125 cm$^3$.
- (ग): cross-section 42 cm$^2$, lateral 87 cm$^2$, total 171 cm$^2$, volume 126 cm$^3$.
- (घ): cross-section 32 cm$^2$, lateral 84 cm$^2$, total 148 cm$^2$, volume 96 cm$^3$.
- (ङ): cross-section 45 cm$^2$, lateral 156 cm$^2$, total 246 cm$^2$, volume 270 cm$^3$.
- (च): cross-section 100 cm$^2$, lateral 380 cm$^2$, total 580 cm$^2$, volume 1000 cm$^3$.