Current location - Training Enrollment Network - Mathematics courses - Chapter 1 Math Practice Eight Times
Chapter 1 Math Practice Eight Times
1,∫∠EAD =∠EAC+∠CAD

∠ ade =∠ b +∠ bad (the outer angle of a triangle is equal to the sum of two non-adjacent inner angles)

∴∠EAD=∠ADE

∴EA=ED

∵EF⊥AD

∴EF is the center line on the side of AD.

2. extend AD to e and connect BE.

∴△BDE≌△ACD

∴∠E=∠CAD=90,BE=AC

In Rt△ABE ∠ bad = 30.

∴BE= 1/2AB

Namely: AC = 1/2ab.