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i have three vectors: a=4,b=3,c=5 that form a right triangle.

vector a is in the positive x direction, vector b is in the positive y direction starting at the tip of a. vector c is the hypotenuse of the triangle with tip at the origin. (see attaced picture .doc file)

the questions are: what is a dot b, a dot c, and b dot c.

i have the solutions in my manual but i dont understand them.

the manual says that from the figure it is clear that a + b + c = 0, where a is perpindicular to b:

a dot b = 0, since the angle between them is 90 degrees:

a dot c = a dot (-a-b)=-|a|^2=-16

and similarly b dot c = -9

i have no idea whay this is true. any help would be appreciated especially a general explanition of what the dot product is

vector a is in the positive x direction, vector b is in the positive y direction starting at the tip of a. vector c is the hypotenuse of the triangle with tip at the origin. (see attaced picture .doc file)

the questions are: what is a dot b, a dot c, and b dot c.

i have the solutions in my manual but i dont understand them.

the manual says that from the figure it is clear that a + b + c = 0, where a is perpindicular to b:

a dot b = 0, since the angle between them is 90 degrees:

a dot c = a dot (-a-b)=-|a|^2=-16

and similarly b dot c = -9

i have no idea whay this is true. any help would be appreciated especially a general explanition of what the dot product is

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