Help maths

Help I don’t get why I always have to convert the angle from degrees to radians even if they don’t specify… like for Q8 the answer is 33.7cm
Which you only get by converting the angle into radians, is this the same for all cases?

(edited 11 months ago)

Reply 1

mqb2766

In degrees
2 pi r * 78.5 / 360 = 46.2
r = 46.2*360 / (2*pi*78.5) = 33.7

(edited 11 months ago)

Reply 2

Muttley79

Original post by Alevelhelp.1

What formula are you using? Arc length = r x angle is only correct of the angle is in radians.

Reply 3

ayuhas21

1st as the angle is in degrees you have to convert it to radians in order top apply the formula.

All you need to remember is 360degrees=2π

So as you have 78.5 degrees you would do 2π x 78.5/ 360 = 1.37(2.dp)

1.37 is your angle in radians so now apply the formula l=rθ and do 46.2/ 1.37 to get the radius(OA) as 33.7

Just remember if it is in degrees and you are using either l=rθ or A=1/2r^2 θ always turn it into radians, hope that helps