Question

The base (unequal side ) of an isosceles triangle is 4cm and perimeter is 20cm. find its area​

Answer 1

Answer:

Let the sides of the triangle be a, a and b.

b = 4cm

perimeter = 20cm

⇒ a + a + b = 20cm

⇒ 2a + 4 = 20

⇒ 2a = 20 - 4 = 16cm

⇒ a = 16/2 = 8cm

s = perimeter/2 = 20/2 = 10cm

\begin{gathered}Area = \sqrt{s(s-a)(s-b)(s-c)}\\ \\ A = \sqrt{10(10-8)(10-8)(10-4)}\\ \\ A = \sqrt{10 \times 2 \times 2 \times 6}= \sqrt{2 \times 5 \times 2 \times 2 \times 2 \times 3}\\ \\ A = 4 \sqrt{15}\ \ cm^2\end{gathered}

Area=

s(s−a)(s−b)(s−c)

A=

10(10−8)(10−8)(10−4)

A=

10×2×2×6

=

2×5×2×2×2×3

A=4

15

cm

2

Area is 4√15 cm².

Answer 2

Answer:

Let the sides of the triangle be a, a and b.

b = 4cm

perimeter = 20cm

⇒ a + a + b = 20cm

⇒ 2a + 4 = 20

⇒ 2a = 20 - 4 = 16cm

⇒ a = 16/2 = 8cm

s = perimeter/2 = 20/2 = 10cm

\begin{lgathered}Area = \sqrt{s(s-a)(s-b)(s-c)}\\ \\ A = \sqrt{10(10-8)(10-8)(10-4)}\\ \\ A = \sqrt{10 \times 2 \times 2 \times 6}= \sqrt{2 \times 5 \times 2 \times 2 \times 2 \times 3}\\ \\ A = 4 \sqrt{15}\ \ cm^2\end{lgathered}

Area=

s(s−a)(s−b)(s−c)

A=

10(10−8)(10−8)(10−4)

A=

10×2×2×6

=

2×5×2×2×2×3

A=4

15

cm

2

Area is 4√15 cm².

Step-by-step explanation:

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