In ∆pqr, pq = 39 cm and pn is an altitude. find pr if qn = 36 cm and rn = 8 cm.

Use the Pythagorean theorem two times:

second time:

17 cm

Step-by-step explanation:

We must first find the length of the height, PN.  Since PN is an altitude, it makes a right angle with QR; this means that PNQ will be a right triangle, as will PNR.  This means we will use the Pythagorean theorem:

a²+b² = c²

Letting h represent PR (since it is the height),

h²+36² = 39²

h²+1296 = 1521

Subtract 1296 from each side:

h²+1296-1296 = 1521-1296

h² = 225

Take the square root of each side:

√(h²) = √(225)

h = 15

PN is 15 cm.

Now we will use it and the other "base," RN, to find PR:

15²+8² = x²

225+64 = x²

289 = x²

Take the square root of each side:

√(289) = √(x²)

17 = x

it would be:

c.parallelogram.