Ex 3.1, 4 - Chapter 3 Class 11 Trigonometric Functions

Transcript

Ex 3.1, 4 Find the degree measure of the angle subtended at the centre of a circle of radius 100 cm by an arc of length 22 cm . ("use " π" = " 22/7) Given 𝑙 = 22 cm r = 100 cm 𝜃 = ? We know that θ "= " 𝑙/𝑟 " " Putting values θ = 𝟐𝟐/𝟏𝟎𝟎 θ = 22/100 radians We need to find θ in degree, so converting into degrees We know that Radian measure = 𝝅/𝟏𝟖𝟎 × Degree measure 22/100 = π/180 × Degree measure 22/100 = 22/180 × 1/7 × Degree measure 𝟐𝟐/𝟏𝟎𝟎 × 𝟏𝟖𝟎/𝟐𝟐 × 7 = Degree measure 126/10 = Degree measure Degree measure = 𝟏𝟐𝟔/𝟏𝟎 = 12° + (𝟔°)/𝟏𝟎 = 12° + ((6 × 60)/10)^′ = 12° + (𝟑𝟔𝟎/𝟏𝟎)^′ = 12° + 36’ = 12° 36’