Question

angle between two vector​

Answer 1

Answer:

A+ B is answer is wrong so tell I will check

Answer 2

Given :

|a + b| = |a - b|

To find :

The angle between a and b

Solution :

we know that,

» If two vectors of magnitudes are acting at an angle, then the magnitude of their resultant is given by parallelogram law that is,

$\sf |a + b| = \sqrt{ {a}^{2} + {b}^{2} + 2abcos \theta }$

similarly,

$\sf |a - b| = \sqrt{ {a}^{2} + {b}^{2} - 2abcos \theta }$

According to Question,

$\dashrightarrow\sf |a + b| = |a - b|$

$\dashrightarrow\sf \sqrt{ {a}^{2} + {b}^{2} + 2abcos \theta } = \sqrt{ {a}^{2} + {b}^{2} - 2abcos \theta }$

$\dashrightarrow\sf {a}^{2} + {b}^{2} + 2abcos \theta = {a}^{2} + {b}^{2} - 2abcos \theta$

$\dashrightarrow\sf \not{a}^{2} + \not {b}^{2} + 2abcos \theta - \not{a}^{2} - \not{b}^{2} + 2abcos \theta = 0$

$\dashrightarrow\sf 2ab \: cos \theta + 2ab \: cos \theta = 0$

$\dashrightarrow\sf 4ab \: cos \theta = 0$

$\dashrightarrow\sf cos \theta = 0$

$\dashrightarrow\sf cos \theta = cos \: 90 \degree$

$\dashrightarrow\sf \theta = 90 \degree$

Thus, Angle between two vectors is 90°