Question (13c) Area of the sector (1 Viewer)

[km1307]

What did everyone get for the question about the length of the interval CD. The question where there is two sectors. Question (13c)
My answer was (Square root 450) I'm not sure if this is right?

 

[Shazer2]

Yeah it is sqrt(450), I read on another thread. How did you get that though?

 

[Menomaths]

I think I got that too.

 

[Hypem]

Simplified it to 15 * sqrt(2)

 

[bedpotato]

sqrt(450)

simplified to 15sqrt(2)

 

[lolwot]

Yeah it is sqrt(450), I read on another thread. How did you get that though?

A ACD = 0.5(30)^2θ
A ACD = 450θ

therefore CDE = 225θ (equal halves)

A CDE =225θ

225θ = 0.5(r)^2θ
r^2 = 450 (simply if ur cool)

i think

pretty hard for a q13

hope i did that in the exam

 

[Recondit]

Let Area CDE = Area ADEB
Area CDE = Area ACB - Area CDE
2(Area CDE) = Area ACB
2(θr²/2) = θR²/2
CD² = 30²/2
CD = sqrt450 = 15sqrt2 cm

R = radius of larger sector ie. CA=30cm
r = radius of smaller sector ie. CD

edit: dammit too slow

 

[Menomaths]

A ACD = 0.5(30)^2θ
A ACD = 450θ

therefore CDE = 225θ (equal halves)

A CDE =225θ

225θ = 0.5(r)^2θ
r^2 = 450 (simply if ur cool)

i think

pretty hard for a q13

hope i did that in the exam

was pretty simple imo

 

[girlworld_club]

the only reason i got this question correct is that i did a past paper question the morning of the exam which was based on this principle.

 

[km1307]

yeah i did that too

 

[kalstar]

Yes I got that.