# find the angle between 2 vectors w=i+3j, vector v=<5, 2>

#### Elissa89

##### Member
I know how to find the cos(theta) between two vectors but I do not know how to find the sin(theta).

vector w=i+3j

vector v=<5, 2>

#### skeeter

##### Well-known member
MHB Math Helper
I know how to find the cos(theta) between two vectors but I do not know how to find the sin(theta).

vector w=i+3j

vector v=<5, 2>
find the cosine, then use a form of the Pythagorean identity ...

$\sin{t} = \sqrt{1-\cos^2{t}}$