A level Maths OCR question help

esha06

this radians question

Reply 1

esha06

Original post by esha06

this radians question

they gave this and said the perimeter is 4 times the arc AB find r

Reply 2

mqb2766

What are you unsure about? The length of an arc and area of a sector are standard formula which you can use/solve simultaneously to get r (and theta).

Reply 3

esha06

Original post by mqb2766

What are you unsure about? The length of an arc and area of a sector are standard formula which you can use/solve simultaneously to get r (and theta).

like what am i meant to use the area to work out because I have no other values

Reply 4

esha06

Original post by esha06

like what am i meant to use the area to work out because I have no other values

nvm i got it

Reply 5

mqb2766

Original post by esha06

like what am i meant to use the area to work out because I have no other values

You need to work out r (and theta) and you have two pieces of information - the perimeter relationship and the area value to get them. So you have two simultaneous equations to form and solve to get r (and theta).