Answer:
40 square units
Step-by-step explanation:
First of all, lets say that square has side
, so, the area unit is 
the diagonal's square is 
CALCULATION OF TRIANGLES'S AREA (there are 4 triangles)

CALCULATION OF MAIN SQUARE AREA

TOTAL AREA

3/5*3/3=9/15
1/3*5/5=5/15
15 is a common denominator.
This is usually used as a proof that triangles have 180°. Look at the attached figures. If you cut off angle A, angle B and angle C and rotate them so that their vertices touch, you form a half-circle out of them (or a straight line). We know that half a circle is 1/2 of 360° or 180; therefore all 3 angles in a triangle must add up to 180°.
Answer:
7/10
Step-by-step explanation: