Last updated at Feb. 3, 2020 by Teachoo
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Ex 10.1, 10 Find the angle between the x-axis and the line joining the points (3, โ1) and (4, โ2). First we find slope of line joining the points (3, โ1) and (4, โ2). We know that slope of line passing through (x1, y1) and (x2, y2) is m = (๐ฆ_2 โ ๐ฆ_1)/(๐ฅ_2 โ ๐ฅ_1 ) Here x1 = 3, y1 = โ1 & x2 = 4, y2 = โ2 Slope of line joining (3, โ1) and (4, โ2) is m = ( โ2 โ (โ1))/(4 โ 3) = ( โ 2 + 1)/(4 โ 3) = ( โ 1)/1 = โ1 Ex 10.1, 10 Find the angle between the x-axis and the line joining the points (3, โ1) and (4, โ2). First we find slope of line joining the points (3, โ1) and (4, โ2). We know that slope of line passing through (x1, y1) and (x2, y2) is m = (๐ฆ_2 โ ๐ฆ_1)/(๐ฅ_2 โ ๐ฅ_1 ) Here x1 = 3, y1 = โ1 & x2 = 4, y2 = โ2 Slope of line joining (3, โ1) and (4, โ2) is m = ( โ2 โ (โ1))/(4 โ 3) = ( โ 2 + 1)/(4 โ 3) = ( โ 1)/1 = โ1 = ( โ2 + 1)/(4 โ 3) = ( โ1)/1 = โ1 Now, Finding Angle from Slope Now, Slope = m = tan ฮธ where ฮธ is the angle between line and positive x-axis So, m = tan ฮธ โ1 = tan ฮธ tan ฮธ = โ1 tan ฮธ = tan (135ยฐ) ฮธ = 135ยฐ So, Required angle = ฮธ = 135ยฐ Rough Ignoring signs tan ฮธ = 1 So, ฮธ = 45ยฐ As tan is negative โด ฮธ will lie in 2nd quadrant, So, ฮธ = 180ยฐ โ 45ยฐ = 135ยฐ
Ex 10.1
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