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chapter7.4b
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à 7.4ïUsing the Pythagorean Theorem.
äïPlease find the square root of the following numbers.
âS
#êëí─êêèí──êêïí──
#êëá9ï=ï3êè á25ï=ï5êèá12ï≈ï3.46
êêêêêêê (rounded to the
êêêêêêêïnearest hundredth)
éS
To find the square root of "9", you should ask the question,
"What number times itself equals nine?"ïThe answer to this question
#is "3".ïSo the square root of "9" is "3".ïThe radical symbol, (√),ïí─
#is used to denote the square root of whatever number is inside. Thus, á9
= 3.
To find the square root of "25", you should ask what number times
itself will equal "25".ïThus, the square root of "25" is "5".
The only numbers that have exact square roots are numbers that are in
the square number sequence.ïThis sequence is given in the following
list.ê1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144,...
Also, combinations of ç numbers like, 4/9, 9/64, and .04 have exact
square roots.ïAll other numbers such as '12' do not have exact square
roots.ïThe best you can do to find the square root of 12 is to use
#your built-in calculator to find that,ïí──
#êêêêêëá12 ≈ 3.46ëTo use the
calculator, just press "L", then press "12", and finally press the "√"
key.
It should be noted that the square root of nine actually has two square
roots.ïThey are 3 and -3; however, you should agree to only take the
positive square root for this and all other square root problems.
# 1êêêëí──
#êêêêïFind á49
èA)ï8êê B)ï7êë C)ï12êë D) å
ü
#êêêêèí──
#êêêêèá49 = 7
Ç B
# 2êêêëí───
#êêêêïFind á144
èA)ï9êê B)ï11êëC)ï12êë D) å
ü
#êêêêïí───
#êêêêïá144 = 12
Ç C
# 3êêêëí──
#êêêêïFind á81
èA)ï11êêB)ï9êë C)ï6êêD) å
ü
#êêêêèí──
#êêêêèá81 = 9
Ç B
# 4êêêëí──
#êêêêïFind á64
èA)ï8êêB)ï22êëC)ï9êêD) å
ü
#êêêêèí──
#êêêêèá64 = 8
Ç A
# 5êêêè ┌───
#êêêê Find │ ╪╤
#êêêêë á 16
#èA)ï╦êê B)ï╩êë C)ï╔êêD) å
ê4êêë3êêè2
#üêêêë í──
#êêêêë│╪╤è╦
#êêêêëá16 ╫ 4
Ç A
# 6êêêëí───
#êêêêïFind á.09
èA)ï3.0êë B)ï.03êè C)ï.3êë D) å
ü
#êêêêïí───
#êêêêïá.09 = .3
Ç C
# 7êêêëí───
#êêêêïFind á400
èA)ï36êêB)ï20êëC)ï40êë D) å
ü
#êêêêïí───
#êêêêïá400 = 20
Ç B
# 8êêêè í───
#êêêê Find á169
èA)ï13êêB)ï14êëC)ï15êë D) å
ü
#êêêêïí───
#êêêêïá169 = 13
Ç A
# 9ëUse yourêëí──
#êêcalculator to findïá18.èRound to the nearest hundredth.
èA)ï4.16êëB)ï3.98êèC)ï4.24êè D) å
ü
#êêêêïí──
#êêêêïá18 ≈ 4.24
Ç C
# 10è Use yourêëí──
#êêcalculator to findïá45.èRound to the nearest hundredth.
èA)ï6.71êëB)ï9.23êèC)ï6.45êè D) å
ü
#êêêêïí──
#êêêêïá45 ≈ï6.71
Ç A
äïPlease use your calculator and the Pythagorean Theorem
êêto find the unknown side of the following triangles.
âêê (Hypotenuse)² = 6² + 8²
#êêêêêèí───────ëí───
#êêêêê = á36 + 64è= á100
êêêêê = 10 ft.
êêêThus the hypotenuse is 10 ft.
@fig401.bmp,25,118
éSThe Pythagorean Theorem states that the square
of the hypotenuse (the long side) of a Right Triangle
is equal to the sum of the squares of the legs
(short sides).ï(hypotenuse)² = (leg1)² + (leg2)²
êIn order to find the length of the unknown
side of the given right triangle, you should
substitute the given numbers into the Pythagorean
Theorem formula.ï(hypotenuse)² = (6ft.)² + (8ft.)²
êêè (hypotenuse)² = 36ft.² + 64ft.²
#èí─────────────èí──────────────êêêí───────
#èá(hyponenuse)² = á36ft.² + 64ft.²êhypotenuse = á100ft.²
êêêThe hypotenuse equals 10 feet.
@fig402.bmp,400,12
@fig403.bmp,400,100
11è Find the length of the unknown side of the following
êêêê Right Triangle.
êêêêè A)ï5êêè B) 6.2
êêêêè C)ï4.5êêïD) å
@fig404.bmp,25,229
üêêè(Hypotenuse)² = 3² + 4²
#êêêè í──────êêê í──
#êëhypotenuse = á9 + 16êïhypotenuse = á25
êêêêhypotenuse = 5
Ç A
12è Find the length of the unknown side of the following
êêêê Right Triangle.
êêêêè A)ï16êêèB) 15
êêêêè C)ï12êêèD) å
@fig405.bmp,25,229
üêêè(Hypotenuse)² = 9² + 12²
#êêêè í────────êêë í───
#êëhypotenuse = á81 + 144êhypotenuse = á225
êêêêhypotenuse = 15
Ç B
13è Find the length of the unknown side of the following
êêêê Right Triangle.
êêêêè A)ï6êêè B) 9
êêêêè C)ï5êêè D) å
@fig406.bmp,25,229
üêêê13² = leg² + 12²
êêêë 169 = leg² + 144
êêêë 169 - 144 = leg²
êêêë 25ï= leg²
#êêêë í──
#êêêë á25 = leg
êêêê 5 = leg
Ç C
14è Find the unknown side rounded to the nearest hundredth.
êêêêè A)ï8.12êê B) 7.65
êêêêè C)ï5.66êê D) å
@fig407.bmp,25,229
üêêè(Hypotenuse)² = 4² + 4²
#êêêè í───────êêê í──
#êëhypotenuse = á16 + 16êïhypotenuse = á32
êêêë hypotenuse ≈ 5.66
Ç C
15è Find the unknown side rounded to the nearest hundredth.
êêêêè A)ï8.49êê B) 8.96
êêêêè C)ï9.02êê D) å
@fig408.bmp,25,229
üêêè(Hypotenuse)² = 6² + 6²
#êêêè í───────êêê í──
#êëhypotenuse = á36 + 36êïhypotenuse = á72
êêêë hypotenuse ≈ 8.49
Ç A
16êFind the length of the unknown side of the given
êêêtriangle and round to the nearest hundredth.
êêêêè A)ï15.31 m.êëB)ï17.56 m.
êêêêè C)ï14.83 m.êëD)ïå
@fig409.bmp,25,229
üêêê16² = x² + 6²
êêêë 256 = x² + 36
êêêë 256 - 36 = x²
êêêë 220 = x²
#êêêêí──è í──
#êêêêá220 = áx²
êêêë 14.83 ≈ x
Ç C
17êFind the length of the unknown side of the given
êêêtriangle and round to the nearest hundredth.
êêêêè A)ï13.27 yds.êèB)ï12.58 yds.
êêêêè C)ï14.26 yds.êèD)ïå
@fig410.bmp,25,229
üêêêï24² = x² + 20²
êêêê 576 = x² + 400
êêêê 576 - 400 = x²
êêêê 176 = x²
#êêêêïí──è í──
#êêêêïá176 = áx²
êêêê 13.27 ≈ x
Ç A