Jawaban:

. Berapa volume kubus jika diketahui panjang sisinya 8 cm?

\bold{Dik :}Dik:

s = 8 cm

\bold{Dit :}Dit:

V = ... ?

\bold{Penjelasan :}Penjelasan:

V = s³

= 8³

= 512 cm³

2. Berapa luas permukaan balok jika panjang 12 cm, lebar 7 cm, dan tinggi 15 cm?

\bold{Dik :}Dik:

p = 12 cm

l = 7 cm

t = 15 cm

\bold{Dit :}Dit:

\rm L_pL

p

= ... ?

\bold{Penjelasan :}Penjelasan:

\rm L_pL

p

= 2 × ((p × l) + (p × t) + (l × t))

= 2 × ((12 × 7) + (12 × 15) + (7 × 15))

= 2 × (84 + 180 + 105)

= 2 × 369

= 738 cm²

3. Berapa volume tabung jika jari-jari tabung 7 cm dan tinggi tabung 12 cm?

\bold{Dik :}Dik:

r = 7 cm

t = 12 cm

\bold{Dit :}Dit:

V = ... ?

\bold{Penjelasan :}Penjelasan:

\begin{gathered}\begin{aligned}\\& \rm V = \pi \times r^2 \times t\\& \rm \ \ = \frac{22}{7} \times 7^2 \times 12\\& \rm \ \ = \frac{22}{7} \times 49 \times 12\\& \rm \ \ = 22 \times 7 \times 12\\& \rm \ \ = 1.848 \ cm^3\\\end{aligned}\end{gathered}

V=π×r

2

×t

=

7

22

×7

2

×12

=

7

22

×49×12

=22×7×12

=1.848 cm

3

4. Berapa tinggi kerucut jika volumenya 3.140 cm³ dan panjang jari-jari 14 cm?

\bold{Dik :}Dik:

V = 3.140 cm³

r = 14 cm

\bold{Dit :}Dit:

t = ... ?

\bold{Penjelasan :}Penjelasan:

\begin{gathered}\begin{aligned}\\& \rm t = \frac{3 \times V}{\pi \times r^2}\\& \rm \ \ = \frac{3 \times 4.312}{\frac{22}{7} \times 14^2}\\& \rm \ \ = \frac{12.936}{\frac{22}{7} \times 196}\\& \rm \ \ = \frac{12.936}{22 \times 28}\\& \rm \ \ = \frac{12.936}{616}\\& \rm \ \ = 21 \ cm\\\end{aligned}\end{gathered}

t=

π×r

2

3×V

=

7

22

×14

2

3×4.312

=

7

22

×196

12.936

=

22×28

12.936

=

616

12.936

=21 cm

5. Berapa volume limas jika alasnya berbentuk persegi dengan panjang sisi 5 cm dan tinggi 12 cm?

\bold{Dik :}Dik:

s = 5 cm

\rm t_lt

l

= 12 cm

\bold{Dit :}Dit:

V = ... ?

\bold{Penjelasan :}Penjelasan:

\begin{gathered}\begin{aligned}\\& \rm V = \frac{1}{3} \times L_a \times t_l\\& \rm \ \ = \frac{1}{3} \times s^2 \times 12\\& \rm \ \ = 5^2 \times 12\\& \rm \ \ = 25 \times 12\\& \rm \ \ = 300 \ cm^3\end{aligned}\end{gathered}

V=

3

1

×L

a

×t

l

=

3

1

×s

2

×12

=5

2

×12

=25×12

=300 cm

3

6. Berapa tinggi alas limas segitiga siku-siku jika volumenya 630 cm³, panjang alas 9 cm, dan tinggi limas 14 cm?

\bold{Dik :}Dik:

V = 630 cm³

a = 9 cm

\rm t_lt

l

= 14 cm

\bold{Dit :}Dit:

\rm t_at

a

= ... ?

\bold{Penjelasan :}Penjelasan:

\begin{gathered}\begin{aligned}\\& \rm t_a = \frac{6 \times V}{a \times t_l}\\& \rm \ \ \ = \frac{6 \times 630}{9 \times 14}\\& \rm \ \ \ = \frac{3.780}{126}\\& \rm \ \ \ = 30 \ cm\\\end{aligned}\end{gathered}

t

a

=

a×t

l

6×V

=

9×14

6×630

=

126

3.780

=30 cm

7. Berapa panjang jari-jari bola jika luas permukaannya 1.256 cm²?

\bold{Dik :}Dik:

\rm L_pL

p

= 1.256 cm²

\bold{Dit :}Dit:

r = ... ?

\bold{Penjelasan :}Penjelasan:

\begin{gathered}\begin{aligned}\\& \rm r = \sqrt{\frac{L_p}{4 \times \pi}}\\& \rm \ \ = \sqrt{\frac{1.256}{4 \times 3,14}}\\& \rm \ \ = \sqrt{\frac{1.256}{12,56}}\\& \rm \ \ = \sqrt{100}\\& \rm \ \ = 10 \ cm\\\end{aligned}\end{gathered}

r=

4×π

L

p

=

4×3,14

1.256

=

12,56

1.256

=

100

=10 cm

8. Berapa panjang jari-jari bola jika diketahui diameternya 20 cm?

\bold{Dik :}Dik:

d = 20 cm

\bold{Dit :}Dit:

r = ... ?

Penjelasan:

\begin{gathered}\begin{aligned}\\& \rm r = \frac{d}{2}\\& \rm \ \ = \frac{20}{2}\\& \rm \ \ = 10 \ cm\\\end{aligned}\end{gathered}

r=

2

d

=

2

20

=10 cm

9. Berapa volume prisma jika alasnya berbentuk persegi panjang dengan panjang 15 cm dan lebar 12 cm dengan tinggi prisma 14 cm?

\bold{Dik :}Dik:

p = 15 cm

l = 12 cm

\rm t_pt

p

= 14 cm

\bold{Dit :}Dit:

V = ... ?

\bold{Penjelasan :}Penjelasan:

\begin{gathered}\begin{aligned}\\& \rm V = L_a \times t_p\\& \rm \ \ \ = (p \times l) \times 14\\& \rm \ \ \ = (15 \times 12) \times 14\\& \rm \ \ \ = 180 \times 14\\& \rm \ \ \ = 2.520 \ cm^3\\\end{aligned}\end{gathered}

V=L

a

×t

p

=(p×l)×14

=(15×12)×14

=180×14

=2.520 cm

3

10. Berapa tinggi prisma segitiga siku-siku jika volumenya 72 cm³ dan luas alas 6 cm²?

\bold{Dik :}Dik:

V = 72 cm³

\rm L_aL

a

= 6 cm²

\bold{Dit :}Dit:

\rm t_pt

p

= ... ?

\bold{Penjelasan :}Penjelasan:

\begin{gathered}\begin{aligned}\\& \rm t_p = \frac{V}{L_a}\\& \rm \ \ \ = \frac{72}{6}\\& \rm \ \ \ = 12 \ cm\\\end{aligned}\end{gathered}

t

p

=

L

a

V

=

6

72

=12 cm