Penjelasan dengan langkah-langkah:
2. Diketahui :
AB = AD = 15 cm
BT = DT = 12 cm
CT = 16 cm
Ditanya :
AT = ....?
AC = ....?
BD = ....?
BC = ....?
K = ....?
L = ....?
Jawab :
AT =
[tex] \sqrt{ {ab}^{2} - {bt}^{2} } \\ = \sqrt{ {15}^{2} - {12}^{2} } \\ = \sqrt{225 - 144} \\ = \sqrt{81} \\ = 9 \: cm[/tex]
AC = AT + CT
= 9 cm + 16 cm
= 25 cm
BD = BT + DT
= 12 + 12
= 24 cm
BC =
[tex] \sqrt{ {bt}^{2} + {ct}^{2} } \\ = \sqrt{ {12}^{2} + {16}^{2} } \\ = \sqrt{144 + 256} \\ = \sqrt{400} \\ = 20 \: cm[/tex]
K = AB + BC + CD + AD
= 15 + 20 + 20 + 15
= 70 cm
L =
[tex] \frac{ac \times bd}{2} \\ = \frac{(at + ct) \times (bt + dt)}{2} \\ = \frac{(9 + 16) \times (12 + 12)}{2} \\ = \frac{25 \times 24}{2} \\ = {300 \: cm}^{2} [/tex]
3. Diketahui :
AB = EF = 15 cm
DC = 25 cm
AE = BF = 12 cm
Ditanya :
AD = ....?
BC = ....?
K = ....?
L = ....?
Jawab :
CF = DE = (DC - AB) ÷ 2
= (25-15) ÷ 2
= 10 ÷ 2
= 5 cm
AD =
[tex] \sqrt{ {ae}^{2} + {de}^{2}} \\ = \sqrt{ {12}^{2} + {5}^{2} } \\ \sqrt{144 + 25 } \\ = \sqrt{169} \\ = 13 \: cm[/tex]
AD = BC = 13 cm
K = AB + BC + CD + AD
= 15 + 14 + 25 + 13
= 67 cm
L = CD × AE
= 25 × 12
=
[tex] {300 \: cm}^{2} [/tex]
4.
[tex]t = \sqrt{ {5}^{2} - {3}^{2} } \\ = \sqrt{25 - 9} \\ = \sqrt{16} \\ = 4 \: cm[/tex]
L = a × t
= 7 × 4
[tex] = {28 \: cm}^{2} [/tex]
K = 7 + 5 + 7 + 5
= 24 cm
5. [(4x+15)° + 4x° + (25-x)°] = 180°
(7x+40)° = 180°
7x = 180° - 40°
7x = 140°
x = 140°/7
x = 20°
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