let the unknown angle be a
so a+90 + 20= 180
If we take 70°,then area (A)=
[tex] \frac{1}{2} sin70xy[/tex]
If we take 90° then area(A)=
[tex] \frac{1}{2} sin90x \times 10 = \frn
therefore y=10.64 cm
By using pythagoras theorem
y^2=x^2+10^2
or, x^2=y^2-100
or, x^2=10.64^2-100
or,x^2=13.2096
or, x= 3.63 cm
