Question

trigonometry class 10 ​

Answer 1

Answer:

Some basic points to remember for Trigonometry class 10

The sum of the three angles of the triangle equals 180 degree

The sum of the length of two sides of a triangle is greater than the third side whereas the difference between the lengths of two sides is less than the third side’s length.

The longest side is equal to the largest angle and vice versa.

Area of the triangle = ½ x base x height

According to Heron’s formula, Area of the triangle is √s(s−a)(s−b)(s−c), where s is the semi perimeter and is calculated by the following formula: ½ (a + b + c) where a, b, c, are the sides of the triangle.

Sine, Cosine and Tangent

When the angle shown is mentioned, the formulae for sine, cosine and tangent are:

Sine: Opposite / Hypotenuse

Cosine: Adjacent / Hypotenuse

Tangent: Sine / Cosine = Opposite / Adjacent

Example, Calculate the angle in a right triangle with the measure of adjacent side being 12 cm and hypotenuse being 20 cm:

The adjacent side = 12 cm

Hypotenuse = 20 cm

Cosine: Adjacent / Hypotenuse

= 12 / 20

cos θ = 12 / 20

θ = cos−1 (0.6)

θ = 99.99

In such a case, sometimes we might need to calculate Cosec, Sec and cot too. In such cases, the formulae to be used are:

Cosec (x) = 1 / sine (x)

Sec (x) = 1 / cos (x)

Cot (x) = 1 / tan (x)