Question

Ajutor doar exercițiul 2 doar punctul c și d . Atât dau coroana

Answer 1

$c)a = 9$

$b = 12$

$d = 25$

$d = \sqrt{{a}^{2} + {b}^{2} + {c}^{2} }$

$25 = \sqrt{ {9}^{2} + {12}^{2} + {c}^{2} }$

$25 = \sqrt{81 + 144 + {c}^{2} }$

$25 = \sqrt{225 + {c}^{2} } \: |( \: )^{2}$

${25}^{2} = 225 + {c}^{2}$

$625 = 225 + {c}^{2}$

${c}^{2} = 625 - 225$

${c}^{2} = 400$

$c = \sqrt{400}$

$c = 20 \: cm$

$A_{l} = 2(a + b) \times c$

$A_{l} = 2(9 + 12) \times 20$

$A_{l} = 2 \times 21 \times 20$

$A_{l} = 840 \: {cm}^{2}$

$A_{t} = A_{l} + 2A_{b}$

$A_{b} = a \times b$

$A_{b} = 9 \times 12$

$A_{b}=108 \: {cm}^{2}$

$A_{t} = 840 + 2 \times 108$

$A_{t} = 840 + 216$

$A_{t} = 1056 \: {cm}^{2}$

$V = a \times b \times c$

$V = 9 \times 12 \times 20$

$V = 2160 \: {cm}^{3}$

$d)b = 5 \: cm$

$c = 20 \: cm$

$d = 21 \: cm$

$d = \sqrt{ {a}^{2} + {b}^{2} + {c}^{2} }$

$21 = \sqrt{ {a}^{2} + {5}^{2} + {20}^{2} }$

$21 = \sqrt{ {a}^{2} + 25 + 400 }$

$21 = \sqrt{ {a}^{2} + 425} \: |( \: )^{2}$

${21}^{2} = {a}^{2} + 425$

$441 = {a}^{2} + 425$

${a}^{2} = 441 - 425$

${a}^{2} = 16$

$a = \sqrt{16}$

$a = 4 \: cm$

$A_{l} = 2(a + b) \times c$

$A_{l} = 2(4 + 5) \times 20$

$A_{l} = 2 \times 9 \times 20$

$A_{l} = 360 \: {cm}^{2}$

$A_{t} = A_{l} + 2A_{b}$

$A_{b} = a \times b$

$A_{b} = 4 \times 5$

$A_{b} = 20 \: {cm}^{2}$

$A_{t} = 360 + 2 \times 20$

$A_{t} = 360 + 40$

$A_{t} = 400 \: {cm}^{2}$

$V = a \times b \times c$

$V = 4 \times 5 \times 20$

$V = 400 \: {cm}^{3}$