(Trigonometric Ratios)

The word

Hipparchus a Greek mathematician, relationships however large or or small measure. The three most used ratio to solve a right angled triangle are the Sine(sin), Cosine(cos) and the Tangent(tan).

The most important task of trigonometry is to find the remaining sides and angles of a triangle when some of its sides and angles are given. This problem is solved by using some ratios of the sides of a triangle with respect to its acute angles. These ratios of acute angles are called Trigonometry ratios of angles.

Let ΔABC, the side opposite to ∠A is ‘a’ , side opposite to ∠B is ‘b’ and side opposite to ∠C is ‘c’. |

In a right angled triangle, 1) Adjacent side(A) is adjacent to the angle "θ”2) Opposite side(O) is opposite the angle “θ",3) the longest side is the Hypotenuse (H). |

SOH-CAH-TOA" is a helpful mnemonic for remembering the definitions of the trigonometric functions sine, cosine, and tangent i.e.,

1) Sine Function: Sinθ= Opposite/ Hypotenuse = O/H (SOH) 2)Cosine Function : Cosθ = Adjacent / Hypotenuse =A/H (CAH)3)Tangent Function : tanθ = Opposite / Adjacent = O/A (TOA) 4) Cosecant Function : cosecθ = Hypotenuse / Opposite = H/O 5)Secant Function: Secθ = Hypotenuse /Adjacent = H/A 6) Cotangent Function : Cotθ = Adjacent / Opposite = A/ H |

1) In a ΔPQR, ∠Q = 90

2) In a ΔABC, ∠B=90

3) In ΔMNO, tan(M)= 5/12, find sin(M) and cos(M).

• SOHCAHTOA -Introduction to Trigonometry

• Trigonometric ratios and their Relation

• Trigonometry for specific angles

• Complementary angles in Trigonometry

• Trigonometric Equations

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