a=9units
Answer:
solution given:
c=40° exterior corresponding angle
In right angled triangle
<c°+B°+90°=180° [Sum of interior angle of a triangle is 180°
B°=180°-40°-90°=50°
Relationship between base and hypotenuse is given by cos angle
Cos c°=base/hypotenuse
Cos40°=a/12
a=Cos40°×12=9.19or 9 units
