Question

13. Find the perimeter and area of a triangle whose sides are 13 cm, 14 cm and 15 cm. ​

Answer 1

Step-by-step explanation:

42 cm is the perimeter

(13+14+15)cm = 42 cm

area in picture

Answer 2

Answer:

$\huge\boxed{P_\triangle=42cm,\ A_\triangle=84cm^2}$

Step-by-step explanation:

$a=13cm,\ b=14cm,\ c=15cm\\\\P_\triangle=a+b+c\\\\P_\triangle=13+14+15=42(cm)\\\\A_\triangle=\sqrt{p(p-a)(p-b)(p-c)};\ p=\dfrac{a+b+c}{2}\\\\p=\dfrac{13+14+15}{2}=\dfrac{42}{2}=21(cm)\\\\A_\triangle=\sqrt{21(21-13)(21-14)(21-15)}=\sqrt{21(8)(7)(6)}\\\\=\sqrt{(3)(7)(4)(2)(7)(3)(2)}=\sqrt{(3^2)(7^2)(4)(2^2)}\\\\=\sqrt{3^2}\cdot\sqrt{7^2}\cdot\sqrt4\cdot\sqrt{2^2}=3\cdot7\cdot2\cdot2=84(cm^2)$