Question

Ada yang bisa nomer 15:'))

Answer 1

|a + b| = √(|a|² + |b|² + 2|a||b|cos t)
|a + b|² = |a|² + |b|² + 2|a||b|cos t
(√42)² = √14² + √14²+ 2√14√14 cost
42 = 14 + 14 + 2.14 cost
42 = 28 + 28cost
42 - 28 = 28cost
14 = 28cost
cost = 14/28
cost = 1/2

samping = 1
miring = 2

depan = √(2² - 1²)
= √(4 - 1)
= √3

sin t = √3/2
= (1/2)√3
= C