Scalar Product (Dot product) of vectors:, are vectors and given like that = (x 1,y 1 ) and = (x 2,y 2 ). We can define the scalar product as:. = = x 1.x 2 +y 1.y 2
Example: and are vectors. If =16, then find the values of x.
Properties of Scalar Product: k 1,k 2 R 3.
Angle between two vectors:
= | |. | |.cos (angle between two vectors) If Ө=0º, vectors are parallels and at the same direction. =| |.| | If Ѳ =90°, vectors are perpendicular to each other.
If the vectors are parallel to each other but at the opposite direction:
Example: Evaluate if the angle between and is 60° and |A| = 20 br, |B|=10br.
Example: With the given points A(-3,4), B(1,-5), C(4,3) and D(-1,6), what is the scalar product of ?
Example: and are givens. If, then find the value of a.
Example: Find cosine of the angle between the vectors. A=(-2,1) and B=(2,2).
Example: If and are perpendicular to each other. Find the value of m.
Example: If the vector and vector are perpendicular to each other, then find the value of m.
Example: Find the scalar product of the vectors and
Example: The triangle in the figure is an isosceles right triangle. If |AE|=|DC| = 2br and |EB|=3 br. Then find
Example: are vectors. If, then find the value of x.