In right △ABC , the right angle is at C, m∠A=30 degrees , and AC=7√5 units.

What is the perimeter of △ABC ?

In right ABC the right angle is at C mA30 degrees and AC75 units What is the perimeter of ABC class=

Respuesta :

Answer:

[tex]P=(7\sqrt{15}+7\sqrt{5})\ units[/tex]

Step-by-step explanation:

see the attached figure to better understand the problem

step 1

Find the length side AB (hypotenuse)

we know that

[tex]cos(30^o)=\frac{AC}{AB}[/tex]

substitute

[tex]cos(30^o)=\frac{7\sqrt{5}}{AB}[/tex]

Remember that

[tex]cos(30^o)=\frac{\sqrt{3}}{2}[/tex]

so

[tex]\frac{\sqrt{3}}{2}=\frac{7\sqrt{5}}{AB}[/tex]

[tex]AB=\frac{14\sqrt{5}}{\sqrt{3}}[/tex]

[tex]AB=\frac{14\sqrt{15}}{3}\ units[/tex]

step 2

Find the length side BC

[tex]sin(30^o)=\frac{BC}{AB}[/tex]

[tex]sin(30^o)=\frac{1}{2}[/tex]

[tex]\frac{1}{2}=\frac{BC}{AB}[/tex]

[tex]BC=\frac{AB}{2}[/tex]

substitute the value of AB

[tex]BC=\frac{\frac{14\sqrt{15}}{3}}{2}[/tex]

[tex]BC=\frac{7\sqrt{15}}{3}\ units[/tex]

step 3

Find the perimeter

[tex]P=AB+BC+AC[/tex]

substitute

[tex]P=\frac{14\sqrt{15}}{3}+\frac{7\sqrt{15}}{3}+7\sqrt{5}[/tex]

[tex]P=\frac{21\sqrt{15}}{3}+7\sqrt{5}[/tex]

[tex]P=(7\sqrt{15}+7\sqrt{5})\ units[/tex]

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