Question

In a triangle ABC , angle A=90 ,AB=5cm , AC=12cm.If AD is perpendicular to BC then AD = ?

Answer 1

area of triangle = (1/2) × base×height
if we take AC as perpendicular then AB will be base.
then area of triangle = (1/2)× 5×12 = 30 cm²
also, by Pythagoras' theorem, 
BC² = AC² +AB²
       =12² + 5² = 169
⇒BC = 13 cm
now, if AD is perpendicular then BC is the base
area of triangle = (1/2)× BC ×AD
⇒30 = (1/2)× 13×AD
⇒AD = 60/13 =4.61 cm

Answer 2

Answer:

Aria of triangle=1/2,×hight×bases

given,∆ABC,angle A=90° ,AB=5cm,AC=12cm,AD=?

We know that,BC^=AB^+AC^

=5^+12^

=169cm^=13cm

There fore,ar(∆ABC)=1/2×AC×AB

=1/2×5×12cm^

=(5×6)cm^=30cm^

Sins,ar(∆ABC)=1/2×BC×AD

= 30 =13/2×AD

=AD=60/13cm