Question

In the adjoining figure, △ABC is a right-angled triangle in which ∠B=90∘ ,∠A=30∘ and AC=20 cm.
Find (i) BC, (ii) AB.​

Answer 1

Answer:

Step-by-step explanation:

1​=20BC​

Or BC=10 cm

By Pythagoras theorem:

(AB)2=(AB)2−(BC)2

=(20)2−(10)2

=300

AB=103

​cm.

solution

Answer 2

$\huge\bold\blue{Given\::-}$

• ∠B=90∘
• ∠A=30∘
• AC=20 cm

$\huge\bold\red{To\:Prove\::-}$

• measure of side BC
• measure of side AB

Sin 30° = BC/AC

$\frac{1}{2} = \frac{bc}{20}$

2bc = 20

BC = 20/2

BC = 10cm

Cos 30° = AB/AC

$\frac{ \sqrt{3} }{2} = \frac{ab}{20}$

2AB = 20√3

AB = 10√3