Question

In ∆ ABC ,<C = 90° , BC =21 unit , AB= 29 unit . Find the value of sinA​

Answer 1

Answer:

By Pythagoras theorem,

AB

2

=AC

2

+BC

2

⇒AC

2

=AB

2

−BC

2

⇒AC

2

=29

2

−21

2

=(29+21)(29−21)=50×8

⇒AC

2

=25×16

⇒AC=5×4=20 units

⇒cosθ=

AB

BC

=

29

21

,

sinθ=

AB

AC

=

29

20

⇒sin2θ+cos

2

θ=

29

2

21

2

+20

2

=

29

2

29

2

=1

⇒cos

2

θ−sin

2

θ=

29

2

21

2

−20

2

=

841

41

Step-by-step explanation:

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