Help urgently maths

Alevelhelp.1

Help I don’t get how to do the ab part…
I understand everything else but just not how they got ab to be cos theta

(edited 10 months ago)

Reply 1

mqb2766

The only time cos(theta) comes into it is when they do the area of the triangle and
OC = r cos(theta)
AC = r sin(theta)
So triangle area = 1/2 base * perp height. ab is not cos(theta).

(edited 10 months ago)

Reply 2

Alevelhelp.1

Original post by mqb2766

The only time cos(theta) comes into it is when they do the area of the triangle and
OC = r cos(theta)
AC = r sin(theta)
So triangle area = 1/2 base * perp height. ab is not cos(theta).

Ohh ok, I’m kinda bad at trig… so I’m still confused as to how oc is r cos theta… and ac is r sin theta

Cos = a/h
Sin = o/h

Reply 3

davros

Original post by Alevelhelp.1

Ohh ok, I’m kinda bad at trig… so I’m still confused as to how oc is r cos theta… and ac is r sin theta

Cos = a/h
Sin = o/h

the whole thing is a sector, so OA is a radius, so OA = r etc.

Reply 4

Alevelhelp.1

Original post by davros

the whole thing is a sector, so OA is a radius, so OA = r etc.

Okayy, but then what about the cos and sin part how to I get them… I don’t get how I know it would be
OC = r cos(theta)

AC = r sin(theta)

I don’t get why it would be the stuff in bold and underlined about ^^