Question

No 2,3,4,5......harus lengkap semua harus diisi
pakai caranya

Answer 1

2) p =  |2a - b|
p² = (2a - b)² = 4|a|² - 4|ab| + |b|²
p² = 4(1)² -4(3) + (4)²
p² = 4 -12+ 16
p² = 8
p = √8
p = 2√2

3) 
cos  Ф = a² +b² -c² / (2 ab)
cos Ф = (9+25 - 49)/ (30 )
cos Ф = - 1/2
Ф = 120° = 120/180 π = 2π/3