Question Number 9715 by tawakalitu last updated on 28/Dec/16
$$\mathrm{Vector}\:\overset{\rightarrow} {\mathrm{A}}\:\mathrm{of}\:\mathrm{magnitude}\:\mathrm{20}\:\mathrm{unit},\:\mathrm{lies}\:\mathrm{in}\:\mathrm{the}\: \\ $$$$\mathrm{direction}\:\mathrm{45}°\mathrm{S}\:\mathrm{of}\:\mathrm{E}\:\mathrm{while}\:\mathrm{vector}\:\overset{\rightarrow} {\mathrm{B}}\:\mathrm{of}\:\mathrm{magnitude} \\ $$$$\mathrm{30}\:\mathrm{units}\:\mathrm{in}\:\mathrm{the}\:\mathrm{direction}\:\mathrm{60}°\mathrm{W}\:\mathrm{of}\:\mathrm{N}. \\ $$$$\mathrm{calculate}\:\mathrm{the}\:\mathrm{scaler}\:\mathrm{product}\:\:\overset{\rightarrow} {\mathrm{A}}\centerdot\overset{\rightarrow} {\mathrm{B}} \\ $$
Answered by sandy_suhendra last updated on 28/Dec/16
Commented by sandy_suhendra last updated on 28/Dec/16
$$\mathrm{the}\:\mathrm{angle}\:\mathrm{between}\:\overset{\rightarrow} {\mathrm{A}}\:\mathrm{and}\:\overset{\rightarrow} {\mathrm{B}}\:=\:\mathrm{165}° \\ $$$$\overset{\rightarrow} {\mathrm{A}}.\overset{\rightarrow} {\mathrm{B}}\:=\:\mid\overset{\rightarrow} {\mathrm{A}}\mid.\mid\overset{\rightarrow} {\mathrm{B}}\mid\:\mathrm{cos}\:\mathrm{165}° \\ $$$$\:\:\:\:\:\:\:\:\:=\:\mathrm{20}×\mathrm{30}×\left(−\mathrm{0}.\mathrm{966}\right) \\ $$$$\:\:\:\:\:\:\:\:\:=\:−\mathrm{579}.\mathrm{6}\:\mathrm{unit} \\ $$
Commented by tawakalitu last updated on 28/Dec/16
$$\mathrm{God}\:\mathrm{bless}\:\mathrm{you}\:\mathrm{sir}.\:\mathrm{i}\:\mathrm{really}\:\mathrm{appreciate}. \\ $$
Commented by geovane10math last updated on 29/Dec/16
$${Other}\:{way}\:... \\ $$$$\mathrm{60}°\:+\:\mathrm{45}°\:+\:{x}\:=\:\mathrm{270}° \\ $$$${x}\:=\:\mathrm{270}°\:−\:\mathrm{105}° \\ $$$${x}\:=\:\mathrm{165}° \\ $$