Question

Find m∠ADB in rhombus ABCD if m∠ACB=40°.

Answer 1

Answer:

m angle ADB= 50°

Step-by-step explanation:

angle A= angle C -( opposite sides of a rhombus)

also, angle B= angle D -(opposite sides of a rhombus)

angle ACB=40°=1/2 angle C.

therefore angle C =40°×2

=80°

therefore angle A=angle C=80°

Hence, angles (A+B+C+D)=360°

therefore angles (80°+B+80°+D)=360°

but, angle B= angle D -(opposite sides of rhombus)

so, angles (160°+2D)=360°

2D=360°-160°

2D=200°

D=100°

but, angle ADB = angle CDB. angle D= angle ADB + angle CDB

100°=2 angle ADB

50°=angle ADB