Question

the semi perimeter of a triangle is 10 cm. if one if one of its side is 5 cm and 7 cm respectly than as​

Answer 1

Perimeter = 5+7+ third side

semi perimeter = 10

5+7+ x = 10

2

12+x = 20

x = 8 cm

Answer 2

Answer:

If find the area of the triangle: 230.417cm²

If find the last side: 8cm

Step-by-step explanation:

I'm not sure what the question is, so I will give 2 possible answers:

If find the last side of the triangle: Since the semi perimeter is 10cm, the perimeter is 20cm, so the last side is 20 - 5 - 7 = 8cm.

If find the area, we will use Heron's formula.

It is used for a triangle area with all 3 lengths known

Here is the formula:

√ p (p−a) (p−b)(p−c)

where p is the semi perimeter.

So,  

√ 10 (10 - 5) (10 - 7) (10 - 8) = 230.417 (3 d.p.)

                                                     or

                                               230.42 (2 d.p.)

                                                      or

                                                 230.4 (1 d.p.)

                                                        or

                                                  230 (nearest integer)

Hope you found this helpful!