Matematika

Pertanyaan

Diketahui : A + B = 45° dan A - B = 30°.
Nilai ( sin A + cos A )( sin B + cos B ) sama dengan ...

A. 1/2 (√3 + √2)
B. 1/2 (1 + √2)
C. 1/2 (√3 - √2)
D. 1/2 (√2 - 1)
E. 1/4 (√3 - √2)

1 Jawaban

  • A+B = 45
    A-B = 30
    (sin A + cos A)(sin B + cos B) = ?
    • (sin A + cos A)(sin B + cos B) = sin A . sin B + sin A . cos B + cos A . sin B + cos A . cos B
    • (sin A + cos A)(sin B + cos B) = [sin A . sin B + cos A . cos B] + [sin A . cos B + cos A . sin B]
    • (sin A + cos A)(sin B + cos B) = [cos (A-B)] + [sin (A+B)]
    •(sin A + cos A)(sin B + cos B) = cos 45 + sin 30 = 1/2 √2 + 1/2 √3 = 1/2 (√2 + √3) => A

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