Question

Find the area of a triangle two sides of which are 18 cm and 10 cm and the

perimeter is 42cm​

Answer 1

Answer:

the answer in three photos ok

Step-by-step explanation:

mark me as brainlist plzz follow me friends ok thanks you very much like me

Answer 2

GivEn:

• Sides of triangle = 18 cm and 10 cm
• Perimeter of triangle = 42 cm

⠀⠀⠀⠀

To find:

• Area of triangle?

⠀⠀⠀⠀

Solution:

$\frak{Here} \begin{cases} & \sf{a = 18\;cm } \\ & \sf{b = 10\;cm } \\ & \sf{c = ?} \end{cases}$

We know that,

⠀⠀⠀⠀

✇ Perimeter of triangle = Sum of its all sides

⠀⠀⠀⠀

$:\implies\sf 42 = 18 + 10 + c$

$:\implies\sf 42 = 28 + c$

$:\implies\sf c = 42 - 28$

$:\implies\bf c = 14 cm$

Therefore, Third side of triangle is 14 cm.

⠀⠀━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Semi - perimeter, s = 42/2 = 21 cm

⠀⠀⠀⠀

✇ Now, Finding Area of triangle using Heron's Formula,

⠀⠀⠀⠀

$\star\;{\boxed{\sf{\purple{Area = \sqrt{s(s - a)(s - b)(s - c)}}}}}$

$:\implies\sf \sqrt{21(21 - 18)(21 - 10)(21 - 14)}$

$:\implies\sf \sqrt{21 \times 3 \times 11 \times 7}$

$:\implies\sf \sqrt{4851}$

$:\implies{\boxed{\frak{\pink{21 \sqrt{11}\;cm^2}}}}\;\bigstar$

$\therefore\;{\underline{\sf{Hence,\;Area\;of\;triangle\;is\; \bf{21 \sqrt{11}\;cm^2.}}}}$