In Figure x and y are unit vector . The vector r make an angle θ with x and y respectively where 0度 < θ < 90度
show that r‧x = r‧y
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r‧x = |r| |x| cosθ
= |r| cosθ
r‧y = |r| |y| cosθ
= |r| cosθ
∴ r‧x = r‧y
我唔明e條數點解個ans 係錦 , 求解釋
更新1:
r‧x = |r| |x| cosθ = |r| cosθ 完全唔明點解會冇左個 |x|