No 28 dong pliss gc butuh banget nih kasih tau dong!
Matematika
andikasena
Pertanyaan
No 28 dong pliss gc butuh banget nih kasih tau dong!
1 Jawaban
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1. Jawaban whongaliem
⇒ ⇒
a . b = (7 x 4 + √p x √p + 4 x - 2)
= 28 + p - 8
= 20 + p
[tex]|a| = \sqrt{ 7^{2} + (\sqrt{p})^{2} + 4^{2} } [/tex]
[tex]= \sqrt{49 + p + 16} [/tex]
[tex]= \sqrt{65 + p} [/tex]
[tex]|b| = \sqrt{ 4^{2} + (\sqrt{p}) ^{2} + ( - 2)^{2} } [/tex]
[tex]= \sqrt{16 + p + 4} [/tex]
[tex]= \sqrt{20 + p} [/tex]
[tex]cos 45^{o} = \frac{a . b}{|a| . |b|} [/tex]
[tex] \frac{1}{2} \sqrt{2} = \frac{20 + p}{ ( \sqrt{65 +p} )( \sqrt{20 + p)} } [/tex]
[tex] \frac{1}{2} \sqrt{2} = \frac{20 + p}{ \sqrt{(65 + p) (20 + p)} } .....kedua ruas .pangkatkan 2[/tex]
[tex] \frac{1}{2} = \frac{ (20 + p)^{2} }{(65 + p) (20 + p)} [/tex]
[tex] \frac{1}{2} = \frac{20 + p}{65 + p} [/tex]
2 (20 + p) = 65 + p
40 + 2p = 65 + p
2p - p = 65 - 40
p = 25 ....... jawaban : C