A Level - Circular Measure

[kittenfelidae]

I feel embarrassed posting this but I have been struggling with the first part for too long now. Please advise on show to 'show' The area is 4.

 

[lev888]

I feel embarrassed posting this but I have been struggling with the first part for too long now. Please advise on show to 'show' The area is 4.

What is the difficulty? Do you know the applicable formula?

 

[Dr.Peterson]

I feel embarrassed posting this but I have been struggling with the first part for too long now. Please advise on show to 'show' The area is 4.

Are you asking about part (b), which asks you to "show" the formula? Or the first part, (a), which asks to "find" the area of the sector?

How to "show" depends on what you "know"! There are various formulas you might have learned, but you can also go back to basics. Draw in the altitude from O to AB, and look at either of the right triangles formed. Find the legs, and then find the area using bh/2.

As for the sector, the first thing is to be aware that they are asking there not for the shaded area (called a circular segment), which is (c), but for the entire "pie piece", whose area is proportional to the angle at the center.

In any case, if you showed us your attempts, we would be able to help you much more quickly. We can use your struggles as the basis for a solution.

 

[firemath]

Also, try to make a 4²pi circle, so you can identify the part of the circle, and use the corresponding formula.

 

[kittenfelidae]

I have made a mistake. I will make another post correcting the question. Thank you for you replies.