The third angle of a triangle is the same size as the first. the second angle is 4 times the third. find the measure of angles.

1st angle 30°

2nd angle 120°

3rd angle 30°

Step-by-step explanation:

Let's call

A = 1st angle

B = 2nd angle

C = 3rd angle

In every triangle it holds

A + B + C = 180°

Now, if the third angle of the triangle is the same size as the first

A = C

If the second angle is 4 times the third

B = 4C

we have then

C + 4C + C = 180° ===> 6C = 180° ===> C = 30°

If C = 30° then A = 30° and B = 120°

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional

it is a secret for it not to be compromised sorry

step-by-step explanation: