问题
填空题
已知三个向量
|
答案
由题意可得|
+OA
+OB
|2=OC
2+OA
2+OB
2OC
+2
•OA
+2OB
•OA
+2OC
•OB OC
=12+22+32+2(1×2×
+1×3×1 2
+2×3×1 2
)=251 2
故|
+OA
+OB
|=5OC
已知三个向量
|
由题意可得|
+OA
+OB
|2=OC
2+OA
2+OB
2OC
+2
•OA
+2OB
•OA
+2OC
•OB OC
=12+22+32+2(1×2×
+1×3×1 2
+2×3×1 2
)=251 2
故|
+OA
+OB
|=5OC