The triangle ABC in the right figure is an isosceles right triangle with a right edge of 4cm. Calculate the area of the shadow part The picture is wrong

The triangle ABC in the right figure is an isosceles right triangle with a right edge of 4cm. Calculate the area of the shadow part The picture is wrong

Let the semicircle and triangle ABC intersect at point d to connect BD. because the triangle formed by any point on the circle and two points with diameter on the circle is a right triangle, obviously the area of the figure formed by BD and the left arc is the same as shadow A. therefore, the area of shadow (a + B) is equal to the area of triangle BCD, that is, half of the area of triangle ABC = = 4 (1 / 2 * 1 / 2 * 4 * 4)