Answers:
- Part (a) 10*sqrt(13)
- Part (b) 10*sqrt(5)
Those values are exact. They approximate to:
10*sqrt(13) = 36.0555
10*sqrt(5) = 22.3607
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Explanation:
Part (a)
If the unknown third side is the hypotenuse then we need to find the value of c when a = 20 and b = 30.
Apply the pythagorean theorem
a^2 + b^2 = c^2
20^2 + 30^2 = c^2
400 + 900 = c^2
1300 = c^2
c^2 = 1300
c = sqrt(1300)
c = sqrt(100*13)
c = sqrt(100)*sqrt(13)
c = 10*sqrt(13) .... exact length
c = 36.0555 ...... approximate length
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Part (b)
If the third side is not the hypotenuse then that must mean c = 30 is the hypotenuse as this side is larger than the 20 cm side. The hypotenuse is always the longest side.
Let a = 20 be the known leg. Let's find the other unknown leg b using the pythagorean theorem.
a^2 + b^2 = c^2
20^2 + b^2 = 30^2
400 + b^2 = 900
b^2 = 900-400
b^2 = 500
b = sqrt(500)
b = sqrt(100*5)
b = sqrt(100)*sqrt(5)
b = 10*sqrt(5) ..... exact length
b = 22.3607 ....... approximate length
