Question

4. In right triangle BDF, right-angled at D, if BD = 15 cm and BF = 17 cm, find
(a) the length of DF; and
(b) the length of DH.
​

Answer 1

Step-by-step explanation:

If you have a right angled triangle this can be calculated using Pythagoras’ theorem.

If corner B is the right angle then no matter where you put A or C. AC at 17cm must be the hypotenuse (longest side).

Pythagoras theorem usually uses ABC as the names of the sides but to save confusion with the points I will use XYZ. So the theorem is X^2 + Y^2 = Z^2.

X^2 + 15^2 = 17^2 is X^2 + 225 = 289

289 - 225 = 64

Square root of 64 = 8.

So the full formula is 8^2 + 15^2 = 17^2. And the length of AB is 8cm.

Answer 2

Step-by-step explanation:

If you have a right angled triangle this can be calculated using Pythagoras’ theorem.

If corner B is the right angle then no matter where you put A or C. AC at 17cm must be the hypotenuse (longest side).

Pythagoras theorem usually uses ABC as the names of the sides but to save confusion with the points I will use XYZ. So the theorem is X^2 + Y^2 = Z^2.

X^2 + 15^2 = 17^2 is X^2 + 225 = 289

289 - 225 = 64

Square root of 64 = 8.

So the full formula is 8^2 + 15^2 = 17^2. And the length of AB is 8cm.