Math, asked by Anonymous, 1 year ago

Prove that Cos60°=1/2????​

Answers

Answered by aman3813
10

Answer:

Draw a Right Angled Triangle with One angle 60 Degrees. Thus this becomes a 30–60–90 Degrees Triangle. Let’s call it a Triangle ABC. Let angle A be 60 Degrees, let angle B be 90 Degrees, so naturally angle C is 30 Degrees.

For a 30–60–90 Degrees Triangle, side opposite to angle 30 Degrees is half the hypotenuse. So in our case if side AB is x then side AC is 2x and side BC is

sqrt(3)*x.

In a Right Angled Triangle, Cos of certain angle is defined as Adjacent Side divided by Hypotenuse.

Therefore Cos(60) would be AB/AC, which is x/2x, which is 1/2.

Thus it is proved that Cos(60) is 1/2.

Other method....

Draw an equilateral triangle ABC.

Let BC be horizontal and A above BC.

All angles 60°

All sides equal length.

Let AD be perpendicular to BC

D is mid point of BC.

cos B = BD / AB

cos 60° = BD / AB

Answer will be 1/2

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Answered by CUTESTAR11
8

Step-by-step explanation:

Draw a Right Angled Triangle with One angle 60 Degrees. Thus this becomes a 30–60–90 Degrees Triangle. Let’s call it a Triangle ABC. Let angle A be 60 Degrees, let angle B be 90 Degrees, so naturally angle C is 30 Degrees.

For a 30–60–90 Degrees Triangle, side opposite to angle 30 Degrees is half the hypotenuse. So in our case if side AB is x then side AC is 2x and side BC is

sqrt(3)*x.

In a Right Angled Triangle, Cos of certain angle is defined as Adjacent Side divided by Hypotenuse.

Therefore Cos(60) would be AB/AC, which is x/2x, which is 1/2.

Thus it is proved that Cos(60) is 1/2.

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