Two intersecting line segments have four right angles.
To solve such a problem, you need to read the known conditions at the first time, go through the known conditions and requirements in your mind, and then use the nature of the circle to solve it.
Extended data:
Formula related to circle:
1, circular area: S=πr? ，S=π(d/2)？ . (d is the diameter and r is the radius).
2. area of semicircle: s semicircle = (π r 2)/2. (r is the radius).
3. Ring area: s great circle -S small circle = π (r 2-r 2) (r is the radius of great circle and r is the radius of small circle).
4. Circumference: C=2πr or c = π d..(d is the diameter and r is the radius).
5. The circumference of a semicircle: d+(πd)/2 or d+π r (d is the diameter and r is the radius).
6. The area of the circle where the sector is located is divided by 360 and multiplied by the angle n of the central angle of the sector, as shown below:
S=n/360×πr？
S=πr？ ×L/2πr=Lr/2(L is arc length and r is sector radius)