Question

In the figure,  ABCD is a cyclic quadrilateral. Seg AB is a diameter. If ∠ADC = 120˚, complete the following activity to find measure of ∠ BAC. 

  ABCD is a cyclic quadrilateral. 

∴ ∠ADC + ∠ABC = 180°

∴ 120˚ + ∠ABC = 180°

∴ ∠ABC =  

But ∠ACB = . ......angle in semicircle In ∆ABC,

∠BAC + ∠ACB + ∠ABC = 180°

∴ ∠BAC +  = 180°

∴ ∠BAC = 

Answer 1

 ABCD is a cyclic quadrilateral.

Comments

Good very