Question

what is cos β? (3,4) cos β =

Explanation:

Step1: Calculate the value of \( r \)

Use the formula \( r=\sqrt{x^{2}+y^{2}} \). Here \( x = 3 \) and \( y = 4 \), so \( r=\sqrt{3^{2}+4^{2}}=\sqrt{9 + 16}=\sqrt{25}=5 \).

Step2: Find \( \cos\beta \)

By the definition of cosine in the coordinate - plane \( \cos\beta=\frac{x}{r} \). Substitute \( x = 3 \) and \( r = 5 \), we get \( \cos\beta=\frac{3}{5} \).

Answer:

\(\frac{3}{5}\)