Question

两道数学题.

1.线段AB上有点C，点C使AC：CB=2:3，点M和点N分别是线段AC和线段CB的中点，若AB=10，求MN和AC的长.
2.如图所示，将一副三角板叠放在一起，使直角的顶点重合于点O，则∠AOC+∠DOB的度数为＿＿.【列算式】

Answer 1

1、
MN=AC/2+BC/2
=AB/2
=5
AC=10*2/(2+3)
=10*2/5
=4
2、
∠AOC+∠DOB
=∠AOB+∠BOC+∠DOB
=∠AOB+∠DOC
=90°+90°
=180°

Answer 2

1、
MN=AC/2+BC/2
=AB/2
=5
AC=10*2/(2+3)
=10*2/5
=4
2、
∠AOC+∠DOB
=∠AOB+∠BOC+∠DOB
=∠AOB+∠DOC
=90°+90°
=180°饿

Answer 3

1、
MN=AC/2+BC/2
=AB/2
=5
AC=10*2/(2+3)
=10*2/5
=4
2、
∠AOC+∠DOB
=∠AOB+∠BOC+∠DOB
=∠AOB+∠DOC
=90°+90°
=180°

不出意外是对了

Answer 4

太简单了