Question

b part please .......

Answer 1

Join AC

Then, angle BCA = 90°

(The diameter forms 90° with the Circumference)

Since CD || AB
=> angle DCB = 25° (alternate Angle)

Angle ACD = angle BCA + angle DCB

=> angle ACD = 90° + 25°

=> angle ACD = 115°

Now, join BD. Hence, ACBD becomes cyclic quadrilateral.

We know that opposite angles are supplementary in a cyclic quadrilateral.

=> angle ACD + angle ABD = 180°

angle ABD = 25° + angle CBD

=> angle ACD + 25° + angle CBD = 180°

=> 115 + 25 + angle CBD = 180°

=> angle CBD = 180 - 115 - 25

=> angle CBD = 40°

angle CED = angle CBD (angles formed on same or equal chords with the circumference are equal)

=> angle CED = 40°