Question 107382
You need to know that in a right angled triangle the sum of the squares of the "legs" is equal to the square of the longest side(the hypotenuse).
This is known as Pythagoras's Theorem and apparently it was used in the building of the Pyramids!
In order to find the perimeter(the distance all round) of the triangle we need to know the length of the third side and since it is a right angled triangle we can use this theorem.
Using algebra the theorem states: a^2+b^2=c^2 where a and b are the "legs" and c is the hypotenuse.
In your question a=3ins and b=4ins and so 3^2+4^2=c^2.
Hence c^2= 9+16=25.
So c={{{sqrt (25)}}}=5 (strictly speaking {{{sqrt (25)}}}= plus or minus 5 but in the context of the question c must =5,since it is a length(a scalar quantity)). So the sides are 3,4 and 5 inches.
Hence the perimeter is 3+4+5=12 inches ANS