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A man observes that when he moves up a distance `c` metres on a slope, the angle of depression of a point on the horizontal plane from the base of the slope is `30^0,` and when he moves up further a distance `c` metres, the angle of depression of that point is `45^0dot` The angle of inclination of the slope with the horizontal is.

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By m-n theorem
`(c+c)cot(theta-30)=(cot15-c cot30)`
`cot(theta-30)=(sin(30-15))/(2sin15sin30)`
`cot(theta-30)=1/2*1/(sinn30)=cot45`
`theta-30=45`
`theta=75^@`.
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