Does anybody know how to do this it's about angles

alpha = 21°

Step-by-step explanation:

You see that this rectangle has four right angles, meaning each of 90 °

That is why it is called a rectangle in the first place. ( The 'rec' in rectangle stands for 'right' or 'streight' and it indicates all angles in the rectangle being 90 °).

Anyway, corner alpha added with the given angle of 69 ° must there fore add up to the value of a streight corner, right?

apha + 69 = 90

alpha = 90 - 69

alpha = 21°

no idea

step-by-step explanation: