Current location - Training Enrollment Network - Mathematics courses - Solve the math problems of the second grade in Shanghai last semester
Solve the math problems of the second grade in Shanghai last semester
As shown in figure ∠ ACB = 90, AC=BC, BE⊥CE in D, AD=2.5cm, DE= 1.7cm, find the length of DE.

Solution: because Be is perpendicular to CE? Advertising vertical CE

So angle E= angle BCA=90 degrees.

Because angle BCE is equal to angle BCA- angle ECA=90 degrees-angle ECA.

Angle DAC=90 degrees-Angle ECA?

So angle e is equal to angle BCE.

Because at △BEC and △CDA,

∠E=∠BCE

∠E=∠BCA

BC=AC

So △ BEC △ CDA (AAS)

So CE=DA=2.5CM.

CD=BE

DC = EC-ED = 2.5cm- 1.7cm = 0.8cm

So BE=0.8CM.