There is a clown’s face on the top of a spinner. The tip of his hat rotated to (-2, 5) during one spin. What is the cosine value of this function?

A) -2
B) 5
C) 5 sqrt 29/29
D) -2 sqrt 29/29

Respuesta :

A lot of the people out there are saying that the answer is negative 2 over sqrt 29. However, I am doing the test, and if you multiply the top and bottom by sqrt of 29, you get D, which is -2 sqrt29/29

Answer:

The correct option is D.

Step-by-step explanation:

It is given that the clown’s face on the top of a spinner. The tip of his hat rotated to (-2, 5) during one spin.

In the point (-2,5), x-coordinate is negative and y-coordinate is positive, it means the point lies in 2nd quadrant. In 2nd quadrant cosine values are negative.

From the below figure it is clear that triangle ABO is a right angled triangle, with perpendicular 5 and base 2.

According to the Pythagoras theorem,

[tex]Hypotenuse^2=Perpendicular^2+Base^2[/tex]

[tex]Hypotenuse^2=(5)^2+(2)^2[/tex]

[tex]Hypotenuse^2=25+4[/tex]

Taking square root both the sides.

[tex]Hypotenuse=\sqrt{29}[/tex]

In a right angled triangle,

[tex]\cos \theta=\frac{Base}{Hypotenuse}[/tex]

Substitute Base=2 and [tex]Hypotenuse=\sqrt{29}[/tex] in the above equation.

[tex]\cos \theta=\frac{2}{\sqrt{29}}[/tex]

Rationalize the denominator.

[tex]\cos \theta=\frac{2}{\sqrt{29}}\times \frac{\sqrt{29}}{\sqrt{29}}[/tex]

[tex]\cos \theta=\frac{2\sqrt{29}}{29}[/tex]

In 2nd quadrant cosine values are negative. So,

[tex]\cos \theta=-\frac{2\sqrt{29}}{29}[/tex]

Therefore the correct option is D.

Ver imagen erinna