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30 votes
30 votes
In ∆STU, S=730 cm, t=270cm and

User JDeuker
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1 Answer

16 votes
16 votes

In this case, we'll have to carry out several steps to find the solution.

Step 01:

side 1 = s = 730 cm

side 2 = t = 270 cm

∠ U = 125 °

side 3 = u = ?

Step 02:

Suppose we know the sides a, b:

a = 730 cm

b = 270 cm

angle C between them:

angle C = 125°

We apply the cosine theorem to find the third side c:


c=\text{ }\sqrt[]{a^2+b^2-2ab\cos C}
c=\sqrt[]{(730\operatorname{cm})^2+(270\operatorname{cm})^2-2(730\operatorname{cm}\cdot270\operatorname{cm})\cos \text{ 125}}

c = 912.088 cm

The answer is:

The length of the side U is 912 cm

User Baa
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