The latest revision of mathematics Huanggang Small Champion Education Edition page 43; Find out the perimeter and area of the shaded part in the following sections. Urgent need! ! ! ! ! ! ! ! ! ! !
The perimeter of the shadow part = 4 ~ 4 π/2 ~ 4× 2× π× 45/360 = 4 ~ 2 π ~ π = 4 ~ 3 π ~.
Area of shaded part
=πR？ ×45 /360 ﹣R×﹙R/2﹚×﹙ 1/2﹚
=πR？ /8﹣R？ /4
=﹙π﹣2﹚R？ /8
=﹙π﹣2﹚×4? /8
=2﹙π﹣2﹚
=2π﹣4﹙㎝? ﹚