Question

4 cos cube 40 degrees-3 sin 50 degrees equals to

Answer 1

Answer:

Cos 3x= 4cos3x-3cosx

Now given : 4 cos3 40 -3sin50 = 4 cos3 40 – 3 sin (90-40)= 4 cos 3 40- 3 cos40 = cos3.40= cos 120= cos(90+30)=-sin30=-1/2

Ans: -1/2

Answer 2

Concept

• The area of mathematics known as trigonometry examines the relationships between triangles' sides and angles as well as the pertinent operations on any angle
• The study of correlations between triangles' side lengths and angles is known as trigonometry.
• In the third century BC, the discipline developed in the Hellenistic culture as a result of the use of geometry in astronomical research..
• A branch of mathematics called trigonometry examines connections between triangles' sides and angles.
• Due to the fact that every straight-sided form can be decomposed into a group of triangles, trigonometry may be found across all of geometry.
• Furthermore, the connections between trigonometry and other areas of mathematics, particularly complex numbers, infinite series, logarithms, and calculus, are incredibly extensive.

Given

The expression $4cos^{3}40-3sin50$ is given

Find

We have to find the value of given expression

Solution

The steps are as follow:

$4 cos^3 40 -3sin50\\\\4 cos^3 40 - 3 sin (90-40)\\\\4 cos^3 40- 3 cos40 \\\\cos^340\\\\cos 120\\\\cos(90+30)\\\\-sin30\\\\(-\frac{1}{2} )\\\\-0.5$

Hence the value of expression $4cos^{3}40-3sin50$ will be -0.5

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