I am just very curious. Your steps looks logical.

1. How do you even know that line AB must be the diameter of a circle? Is it just based on the figure that AB seems to be the diameter?

2. What gave you the impression that the two small triangles have the same area? Is it because they look identical on the figure?

Thanks.

The steps say AB=BC so both triangle is the same

Want to understand how triangle minus semi circle will be shaded part. Thanks ant it only part of half semi circle included in the triangle. Why minus 1/4 of semi circle from the small triangle

I still don’t understand which semi circle area minus from triangle will make the shaded area! Can you help draw and explain pls

The right angle isosceles triangle is made up of 2 smaller isosceles triangle..The semi-circle is made up of one of the smaller isosceles triangle and 2 remaining equal portion of it(let it be called x)... when you take the area of the semi-circle minus the area of the smaller isosceles triangle then divide it by 2. You are finding the area of “x”. You then take area of the smaller isosceles triangle minus away area of “x” to find the shaded area.
My explanation is not very good ..but this is what I’ve understood from what Kavin is doing.. HAHA

Got ya.... thank you so much

No prob ! :D