or
or
→A = 6ˆi - 3ˆj - 3ˆk →B = 2ˆi + 2ˆj + ˆk
→A ও →B এর মধ্যবর্তী কোণ θ হলে,
cos θ = (→A ⋅ →B)/(||→A|| ||→B||)
→A ⋅ →B = (6ˆi - 3ˆj - 3ˆk) ⋅ (2ˆi + 2ˆj + ˆk)
= 12 - 6 - 3
= 3
||→A|| = ||6ˆi - 3ˆj - 3ˆk||
= √(6^2 + (-3)^2 + (-3)^2)
= √45
= 3√5
||→B|| = ||2ˆi + 2ˆj + ˆk||
= √(2^2 + 2^2 + 1^2)
= √9
= 3
cos θ = 3/(3√5 * 3)
cos θ = 1/√5
θ = arccos(1/√5)
θ ≈ 69.98°
উত্তরঃ 69.98°
