Trigonometric Functions (1 Viewer)

[bouncing]

Hey guys, cant seem to work this out

5) A chord PQ, 24 cm long is 5cm from teh centre of the circle. Calculate the length of the arc PQ

so i know that the radius is x
cos by pythagaros' theorem 12^2+5^2=x^2
.'.x=13 ... but how do you find the arc?
l=rtheta
but i dont know what theta is :|

umm same with
A chord AB of a circle with centre 0 has length 16cm. If the radius of the circle is 10cm, calc the magnitude of the angle AOB

 

[Trebla]

Hey guys, cant seem to work this out

5) A chord PQ, 24 cm long is 5cm from teh centre of the circle. Calculate the length of the arc PQ

so i know that the radius is x
cos by pythagaros' theorem 12^2+5^2=x^2
.'.x=13 ... but how do you find the arc?
l=rtheta
but i dont know what theta is :|

umm same with
A chord AB of a circle with centre 0 has length 16cm. If the radius of the circle is 10cm, calc the magnitude of the angle AOB

You've found all sides of the triangle POQ/AOB. So just apply the cosine rule to find the angle at the centre. Alternatively, since the triangle is isosceles you can bisect the chord with a perpendicular line and find half of the angle using standard right-angled trigonometry.

 

[bouncing]

oh oops
i forgot about the cosine rule
thanks !!

 

[hscishard]

Did anyone get 10.26 for this first one?

 

[ohexploitable]

Did anyone get 10.26 for this first one?

I got 30.58

 

[hscishard]

How gay now I got 30.58. Why did you divide it by 2?

Ooo edit: you edited

 

[ohexploitable]

How gay now I got 30.58. Why did you divide it by 2?

Ooo edit: you edited

Yay!

When I did the circumference I did 13pi instead of 26pi.

 

[bouncing]

yup 20.58 is the answer (Y) nice work