Calculus

Vector Algebra ? Vector Addition ? Scalar Multiplication ? How about the product of two vectors? 1. Dot Product ?v ? ?u 2. Cross Product ?v ? ?u Before the geometry, Determinant ? Determinant of a 2? 2 matrix, ? ? ? ? a b c d ? ? ? ? = ad ? bc ? Determinant of a 3? 3 matrix, ? ? ? ? ? ? a 1 a 2 a 3 b 1 b 2 b 3 c 1 c 2 c 3 ? ? ? ? ? ? = a 1 ? ? ? ? b 2 b 3 c 2 c 3 ? ? ? ? ? a 2 ? ? ? ? b 1 b 3 c 1 c 3 ? ? ? ? + a 3 ? ? ? ? b 1 b 2 c 1 c 2 ? ? ? ? =a 1 (b 2 c 3 ? b 3 c 2 )? a 2 (b 1 c 3 ? b 3 c 1 ) + a 3 (b 1 c 2 ? b 2 c 1 ) Example 1 1. ? ? ? ? ?1 2 3 5 ? ? ? ? = ?5? 6 = ?11 2. ? ? ? ? ? ? 2 4 6 ?1 3 5 7 2 6 ? ? ? ? ? ? = 2 ? ? ? ? 3 5 2 6 ? ? ? ? ? 4 ? ?

Vector Algebra ? Vector Addition ? Scalar Multiplication ? How about the product of two vectors? 1. Dot Product ?v ? ?u 2. Cross Product ?v ? ?u Dot Product Take 3-D for example, De?nition If two vectors ?a =< a 1 , a 2 , a 3 > and ?b =< b 1 , b 2 , b 3 >, then the dot product (inner product, scalar product) of ?a and ?b is de?ned as ? a ? ? b = a 1 b 1 + a 2 b 2 + a 3 b 3 Example < 2,?4 > ? < 3, 5 > = ?14 (?i + 2?j ? 4?k) ? (?2?i +?j + 3?k) = ?12 Remark: Dot product gives a scalar. Properties: 1. ?a ??a = a2 1 + a2 2 + a2 3 = |?a|2 2. ?a ? ?b = a 1 b 1 + a 2 b 2 + a 3 b 3 = ?b ??a 3. ?a ? (?b + ?c) = ?a ? ?b +?a ? ?c 4. (c?a) ? ?b = c(a 1 b 1 + a 2 b 2 + a 3 b 3 ) = c(?a ? ?b) = ?a ? (c?b) 5. ?0 ??a = 0