If a + b + c = 0 and | a |=5,| b |=3 and | c |=7 then angle between a and b is

Step-by-step solution

Given, a + b + c = 0 and | a |=5,| b |=3,| c |=7 a + b =- c On squaring both sides, we get ( a + b )²=(- c )² | a + b |²=| c |² | a |²+| b |²+2 a b =| c |²( be the angle between a and b ) (5)²+(3)²+2| a || b | =(7)² 25+9+2 5 3 =49 30 =15 = 1 2 = 60^ = 3