同学们,你一定知道,三角形三内角的和等于180°。如果分别以三角形三个顶点为圆心,以1厘米为半径画圆,如右图,想一想阴影部分的面积和是多少?通过移动以后,阴影部分成为一个半径1厘米的半圆。即阴影部分的面积为3.14×12÷2=1.57(平方厘米)。用同样的思路,想一想右面这些图形中 Students, you must know that the sum of the three interior angles of the triangle equals 180 °. If you take the three vertices of the triangle as the center and the circle as the radius of 1 centimeter, as in the picture to the right, consider the area and area of ​​the shaded area. After moving, the shaded area becomes a semicircle with a radius of 1 cm. That is, the area of ​​the shaded area is 3.14 × 12 ÷ 2 = 1.57 (square centimeters). With the same idea, think of the right of these graphics