Answered

Sumali sa IDNStudy.com at makakuha ng mga sagot sa iyong mga tanong. Makakuha ng impormasyon mula sa aming mga eksperto, na nagbibigay ng maaasahang sagot sa lahat ng iyong mga tanong.

The sides of a triangle are 80cm, 100cm, 140cm. Determine the radius of the circumscribing circle.


Sagot :

There are two ways to find the radius of circumscribing circle of a triangle (triangle  inside the circle and whose three vertices are on the circle).

Choose one that you can easily remember:

Method A:
1.) Find the semi-perimeter (s) of the triangle, where a, b, and c are the sides         
     of the triangle:

     s = (a + b+ c) ÷ 2

2.)  Solve for the radius (r) given the semi-perimeter (s) of the triangle, and the      
      the sides a, b, and c:
 
     r = [tex] \frac{abc}{4 \sqrt{s(s-a)(s-b)(s-c)} } [/tex]

Solution using Method A:
a = 80 cm;  b = 100 cm;  c = 140 cm

Find the triangle's semi-perimeter: (half of the triangle's perimeter)

s = (80 + 100 + 140) ÷ 2

s = 320 cm ÷ 2

s = 160 cm


Solve for radius given the semi-perimeter (160 cm) and sides a, b, c:


r = (abc) ÷ [tex]4 \sqrt{s(s-a)(s-b)(s-c)} [/tex]

r =  [tex] \frac{(80cm)(100cm)(140cm)}{4 \sqrt{140cm(160cm-80cm)(160cm-100cm)(160cm-140cm)} } [/tex]

r = [tex] \frac{1,120,000cm ^{3} }{4 \sqrt{(160cm)(80cm)(60cm)(20cm)} } [/tex]

r = [tex] \frac{1,120,000cm ^{3} }{4 \sqrt{15,360,000cm ^{4} } } [/tex]

r =[tex] \frac{1,120,000cm ^{3} }{4 (3,919.18cm ^{2}) } [/tex]

r = [tex] \frac{1,120,000cm ^{3} }{15,676.72cm ^{2} } [/tex]

r ≈ 71.44 cm

ANSWER:  The radius of circumscribing circle is 71.44 cm.

Method B:

r = [tex] \frac{abc}{ \sqrt{(a+b+c)(b+c-a)(c+a-b)(a+b-a)} } [/tex]

Substitute the given measurements of sides a, b and, c, then evaluate.
The result is the same.