Let the degree of this angle be x, then its complementary angle is 90-X,
X=2*(90-X),X=60
So its complementary angle = 180-60= 120 degrees.
2.
y^2+y+ 1/4=(y+ 1/2)^2
3.
When the side length increases, it is a+5, and the area is (A+5) 2.
So the increased area:
(a+5)^2-a^2
=(a+5+a)(a+5-a)
=(2a+5)*5
= 10a+25
4.
S= bottom * height /2
Height16a4-2a2+1/4 = (4a-1/2) 2
So s = 1/2 * (4a+ 1/2) 3.
5.
75/ 100=7.5* 10^(- 1)