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How to find the value of Cos 120 0. As mentioned in the solution given below, 120° can be represented in terms of two angles i.e. either 90° or 180°. We can show that 120 degrees can be represented in two angles, whose value can be taken from trigonometry table. 90 degree and 180 degree. 180° – 60° = 120° ———– (1)
Find the value of cos 120 ° We know that . cos α + β = cos α cos β-sin α sin β. Now by substituting the value of α = 90 ° and β = 30 ° in the trigonometric identity we get. cos 90 ° + 30 ° = cos 90 ° cos 30 °-sin 90 ° sin 30 ° ⇒ cos 90 ° + 30 ° = 0-1 × 1 2 ∵ cos 90 ° = 0, sin 90 ° = 1 and sin 30 ° = 1 2 ⇒ cos 120 ...
Dec 25, 2016 · How do you find the value of #cos 120#? Trigonometry Trigonometric Identities and Equations Double Angle Identities. 1 Answer
The value of cos 1° cos 2° cos 3° ..... cos 120° is _____. Open in App. Solution. cos 1 ...
The six trigonometric functions are sine, cosine, secant, cosecant, tangent and cotangent. By using a right-angled triangle as a reference, the trigonometric functions and identities are derived: sin θ = Opposite Side/Hypotenuse. cos θ = Adjacent Side/Hypotenuse. tan θ = Opposite Side/Adjacent Side.
Oct 30, 2015 · Explanation: cos(− 120∘) = cos120∘. = cos(180∘ − 60∘) = − cos60∘. = − 1 2. Note: Above I have used the 180∘ rule. Alternatively I could also have used the 90∘ rule, or the compound angle formulae for either sin or cos, or a number of other possible methods as well, and each would result in exactly the same final answer.
Step a: Solve the 2nd equation to find y. Step b: Substitute the value of y in one of the given equations to obtain the value of x. Step c: Inject/ substitute x in the 2nd equation to make it a linear equation in one variable. Step d: In 1st equation, solve for x in terms of y. Q. How many steps are required to solve the equaltion below: x−8 ...
Law of Cosines in Trigonometry. The law of cosine or cosine rule in trigonometry is a relation between the side and the angles of a triangle. Suppose a triangle with sides a, b, and c and with angles A, B, and C are taken, the cosine rule will be as follows. According to cos law, the side “c” will be: c2 = a2 + b2 − 2ab cos (C) It is ...
Q. Prove that c o s 510 ∘ c o s 330 ∘ + s i n 390 ∘ c o s 120 ∘ = − 1 Q. If cos 12 0 + sin 12 0 cos 12 0 − sin 12 0 = tan x 0 , what is the value of x ?
Mar 6, 2018 · 1 Answer. Jane. Mar 6, 2018. cos120 = cos(180 − 60) = cos180cos60 + sin180sin60. (using the formula, cos(a + b) = cosacosb +sinasinb. Now,we know, cos180 = − 1,cos60 = 1 2,sin180 = 0,sin60 = √3 2. So,putting the value,we get, cos120 = − 1 × (1 2) +0 × √3 2 = − 1 2 = − cos60. Remember the formula cos(180 − θ) = − cosθ for ...
