Question

What is cos(45°)?

Answer 1

Answer:

$\rm \dfrac{\sqrt2}{2}$

Step-by-step explanation:

A right angled ∆ is given to us and we need to find out the value of cos 45° ( with rationalized denominator ) . As we know that in a right angle ∆ , the value of cosine is ,

$\rm\implies cos\theta =\dfrac{base}{hypotenuse}$

In the given triangle ,

• Value of base = 1
• Value of hypotenuse = √2

On substituting the respective values ,

$\rm\implies cos45^\circ =\dfrac{1}{\sqrt2}$

For rationalizing the denominator , multiply numerator and denominator by √2 , we have,

$\rm\implies cos45^\circ=\dfrac{1(\sqrt2)}{(\sqrt2)(\sqrt2)}$

Simplify ,

$\rm\implies \boxed{\pink{\frak{ cos45^\circ=\dfrac{\sqrt2}{2} }}}$