here is an isosceles triangle with base angles 30 degrees. Its area is 40cm squared. Find its perimeter to 3s.f.

here is an isosceles triangle with base angles 30 degrees Its area is 40cm squared Find its perimeter to 3sf class=

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Answer:

Step-by-step explanation:

We can find that angle P = 180 - 30 - 30 = 120.

Constructing an angle bisector that divides P into two 60 degree angles and meets at point S in RQ, also dividing RQ into 2 equal segments, we can find the area because the ratio of the sides of a 30-60-90 degrees triangle is 1: sqrt3: 2.

Making an equation where x = PS and RS = x[tex]\sqrt3[/tex] and PR = 2x, we get:

[tex]\frac{{x}\cdot{x\sqrt3}}{2}=40[/tex]

[tex]x\cdot x\sqrt3=80[/tex]

[tex]x^2\sqrt3=80[/tex]

[tex]x^2=\frac{80}{\sqrt3}[/tex]

[tex]x=\sqrt\frac{80}{\sqrt3}[/tex]

Simplifying this in a calculator, we get:

x = 6.79617697939

Now we know that x = 6.79617697939, and PR = 2x, and because PR = PQ, combined they make 4x = 4 x 6.79617697939 = 27.1847079176.

Since RS = [tex]x\sqrt3[/tex], RQ = [tex]2x\sqrt3[/tex] = 2 x 6.79617697939[tex]\sqrt3[/tex] = 13.5923539588[tex]\sqrt3[/tex] = 23.5426476511. Adding 27.1847079176 and 23.5426476511, we get:

50.7273555687

Which is around

50.727

Solution: 50.727 cm

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