Given the triangle below, find the measure of angle
A
. Picture is not drawn to scale

A = 62.35°

A = 62° (Appropriately)

Step-by-step explanation:

To solve for the value of angle A, we employ the COSINE FORMULA.

cos A = (b² + c² - a²) / 2bc

cos B = (a² + c² - b²) / 2ac

cos C = (a² + b² - c²) / 2ab

Where:

A,B,C are the angles of the triangle.

a,b,c are the lengths of the sides

a= 20

b= 16

c= 21

Cos A = (16² + 21² - 20²) / 2*20*16

Cos A = (256 + 441 - 400) / 640

Cos A = 297 / 640

Cos A = 0.464

A = 62.35

A = 62 Appropriately.

correct answer:

i^31 = -i

he used the algebra tiles correctly.

step-by-step explanation:

given : 3x(2x-1)

solution :

since he used algebra tiles .

armando's solution is the same in the solution shown in figure

as he distributed 2x into x and x and wrote them vertically

and also write   -1 vertically

and 3x into x and x and x and wrote it horizontally

performing the multiplication in the algebra tiles we get

and solving the given expression :

3x(2x-1)

since solving the expression using tiles   and solving the expression algebraically we get the same answer

thus   we can choose the first statement as the answer to this problem which is "he used the algebra tiles correctly".