Question

Find the height of equilateral triangle whose side is 15 cm​

Answer 1

ANSWER :-

$area \: \: of \: \: triangle = \frac{ \sqrt{3 } {a}^{2} }{4} \\ \\ = \frac{ \sqrt{3} }{4} \times 15 \times 15 \\ \\ = \frac{225 \sqrt{3} }{4} \\ \\ we \: \: know \: \: the \: \: area \: of \: \: triangle \: \: \\ \\ = \frac{1}{2} \times b \times h \\ \\ \frac{225 \sqrt{3} }{4} = \frac{1}{2} \times 15 \times h \\ \\ h = \frac{225 \sqrt{3} }{4} \times 2 \times \frac{1}{15} \\ \\ h = \frac{15 \sqrt{3} }{4} \\ \\ h = 7.5 \sqrt{3}$

Answer 2

Explanation:

in ABC triangle

AB=15 , BC =15, CA=15

base BC,

half of base OB = 7.5

OA is hight

use pythagorus theoram

OA=√(AB2. - OB2)

√{(15)2- (7.5)2}

OA =12.99= 7√3