9.A new classroom is 10.5 metres by 5.2 metres. Each child needs 2m2 of space.

How many children are allowed in the classroom? Round to the nearest whole number

14

Step-by-step explanation:

(10.5×5.2)÷(2×2)

=13.65

~14

last option

step-by-step explanation:

given that δdef is right and isoceles,

assuming that side df is the hypotenuse means that de an ef are the other 2 sides that intersect at 90° and are of equal length.

because they are of equal length, we can say that they are congruent

because they intersect at 90°, their slopes must be opposite reciprocals.

only the last option satisfies these conditions.