SinA=1/2, find the value of CosA?

By using the identity (SinA)^2+(CosA)^2=1 1/4+(CosA)^2=1 (CosA)^2=3/4 CosA=+ sqrt(3/4) or - sqrt(3/4)

What is the perimeter of a rectangle when the length= 30 cm and the width=20 cm?

The perimeter is when you add all four sides together. Two of the sides are the length (30). So 30+30= 60 cm, but we aren't done yet. Two of the sides are the width (20). So 20+20=40 cm. Now we have to add the two answers we got together so 60+40= 100 cm. The perimeter is 100 cm. (You also could ass 30+30+20+20= 100 cm).

What are the two types of cells that make up every living organism on Earth? Name at least three differences between the two.

The two types of cells that make up every living organism on Earth are eukaryotic and prokaryotic cells. Three differences: -Eukaryotic cells have a nucleus, while prokaryotic do not. -Eukaryotic cells have a mitochondria, while prokaryotic do not. -Prokaryotic cells do not make up multi-cellular organisms (such as animals and plants), only bacteria.