Question

I need help with Q8 and Q9

Answer 1

we know that angle abc = angle dcb so we have to inly find angle bac.
we know that
A+B+C= 180
we know b nd c so we easily find a
a +69+31 =180
a+100=180
a=180-100
a=80
so we find that bac=80
which is equal to bdc
therefore angle bdc is equal to 80°.