Question

In an adjoning figure triangle ABC is a right angled at B.If angle A=30*. and AC=20cm,find1)BC and 2)AB​

Answer 1

Answer:

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Answer 2

∠B= 90°

∠A=30°

Therefore , AC is the hypotenuse = 20cm

$sinA= \frac{BC}{AC}= \frac{BC}{20}\\ sin A=sin 30^o = \frac{1}{2}\\ therefore , \frac{1}{2} =\frac{BC}{20} => BC= 10 cm$

$AB^{2} +BC^{2} =AC^{2} \\=>AB^{2}=400-100=300 \\ => AB= \sqrt{300} =10\sqrt{3}cm$