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The second day of the first volume of mathematics. You'd better bring some explanations and answers.
As shown in the figure, CD is the bisector of triangle ABC, with angle DCB = 30 and BC = AC+AD. Find the degree of angle a ..

Take point e on CB, let CE=CA, connect AE,

∫∠ACB = 60,

∴△ACE is positive △,

∴∠AEC=60,

∫△ACD?△ECD

∴AD=DE=BE,

Let ∠DAE=X,

So DEA = x,

∠BDE=2X,

∠DBE=2X,

∠DEC=4X,

That is ∠AEC+∠AED=60+X=4X,

The solution is x = 20.

∴∠BAC=60 +20 =80