Question

Consider the following figure.

Answer 1

Answer:

80 units.

Step-by-step explanation:

The rectangle ABCD is drawn and attached in the image below. The diagonal BD measures 100 units, the side BC measures 60 units.  We need to find the measure of side DC which is represented by x in the figure.

Note that a Right Angled Triangle DCB is being formed with BD as the hypotenuse and sides BC and DC as its two legs. The Pythagoras Theorem relates the length of hypotenuse and the two legs of the Right Angled Triangle as:

$c^{2}=a^{2}+b^{2}$

c is the length of hypotenuse = 100

a is the length of one leg = 60

b is the length of second leg = x

Using these values, we get:

$100^{2}=60^{2}+x^{2}\\\\ x^{2}=100^{2}-60^{2}\\\\ x^{2}=6400\\\\ x = 80$

Therefore, measure of the side DC is 80 units