∠ACB = 180-∠BAC-∠ABC = 180-48-58-30 = 44

Let AB=AD= 1,

Sine theorem:

AB/sinACB=AC/sinABC，

AC = ABsinABC/Sina CB = 1×sin(58+30)/sin 44 = sin 88/sin 44 = 2cos 44

Cosine theorem:

CD？ =AC？ +AD？ -2AC。 ADC cosdac

=4cos？ 44 + 1-2×2cos44 cos 16

= 4 cos 44(cos 44-cos 16)+ 1

=-8cos 44 sin 30 sin 14+ 1

=-4cos44 sin 14 + 1

=-2[sin58 -sin30 ]+ 1

=2-2sin58

2( 1-sin58 )=2(sin？ 29 -2sin29 cos29 +cos？ 29 )=2(cos29 -sin29)？

CD =√2(cos 29-sin 29)= 2(sin 45 cos 29-cos 45 sin 29)= 2 sin 16

Sine theorem:

CD/sin 16 =AD/sinACD

Sina CD = adsin 16/CD = sin 16/2 sin 16 = 1/2，

∠ACD=30