Question

the area of a right angle triangle is 6 CM square if the base measures 4 cm and its hypotenuse measures 5 cm find its perimeter

Answer 1

area of a triangle is 1/2*base*height
hence height=area*2/base=3cm
perimeter=height+base+hypotenuse
                =3+4+5
                =12cm

Answer 2

Lets use the Pythagoras theorem:

a^2 + b^2= c^2
a^2 + 4^2=5^2
a^2+16=25
a^2=25-16
a^2=9
a= Root 9
a=3

Now add up all the sides:
a + b+ c= perimeter of triangle
3+4+5=  perimeter of triangle
perimeter of triangle is 12 cm