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Four hearts in mathematics
External heart:? The intersection of perpendicular bisector on three sides of a triangle.

The center of the triangle is circumscribed by a circle. ?

Inner heart: the intersection of bisectors of three angles of a triangle.

The center of a triangle inscribed with a circle. ?

Vertical center: the intersection of three heights of a triangle. ?

Center of gravity: the intersection of three sides of a triangle. (the center of gravity is biased to one side.

The distance between points is equal to one third of the center line of this side. )

Center: Only regular triangles (equilateral triangles) have centers.

At this time, the center of gravity, inner heart, outer heart and heart are integrated. ?

As shown in the figure:

∵? G is the center of gravity of the triangle ABC, BD=CD, AE=CE,

And AD⊥BE, BC=a, AC=b,

∴? BD=CD=a/2? ,AE=CE=b/2? ,

DG=AG/2? ,EG=BG/2? ,

AG & ampsup2+EG & amp; sup2AE & ampsup2,BG & ampsup2+DG & amp; sup2= BD & ampsup2? ,

∴? AG & ampsup2+EG & amp; sup2+BG & amp; sup2+DG & amp; sup2AE & ampsup2+BD & amp; sup2? ,

∴ag&; sup2+(BG/2)& amp; sup2+BG & amp; Sup2+(AG/2) and Ampsup2 = (B/2)&; sup2+(a/2)& amp; sup2?

∴? AG & ampsup2+BG & amp; sup2=(a & amp; sup2+b & amp; sup2)/5? ,

Again? AG & ampsup2+BG & amp; sup2AB & ampsup2

∴? AB & ampsup2=(a & amp; sup2+b & amp; sup2)/5? ,

∴? AB =√[5(a & amp; sup2+b & amp; sup2)]/5? ,

Or? AB =√(5a & amp; sup2+5b & amp; sup2)/5? .