Answer:

Explanation:
A right angled triangle is given to us with the sides 3 and 4 . We need to find the value of unknown angle that is
.
So , here the measure of hypotenuse is 5 units .
And the measure of base is 4 units .
Let us take the unknown angle be
. That is let us take ,
So here we can use the trigonometric ratios of cosine . The cosine can be expressed as a ratio of base and hypotenuse of a right angled triangle . Here ∆ABC . So , cosine is ,

Put on the respective values ,
