Combined Correction for a Distance of 2500 m is

Combined correction for a distance of 2500 m is 0.42 m.

Solution

Correction due to curvature,

C_C=d²/2R

where,

d = horizontal distance between 2 points (in km)

R = radius of curvature of earth = 6370 kms

C_C=0.0785d²

d is substituted in kms and C_C value will be in m

Correction due to curvature is always negative

Correction due to refraction,

C_R=17 C_C 

C_R =0.0112d²

d = horizontal distance between 2 points (in km)

C_R = corrections due to refraction (in m)

Correction due to refraction is always positive

Combined correction,

C = C_R  – C_C

C= 1/7C_C – C_C 

C= –6/7 C_C 

C= -0.0673d²

d is substituted in kms and C value will be in m

Combined correction for a distance of 2500 m is

C=0.0673×2.5² (negative)

(d = 2500 m = 2.5 km)

C = 0.42 m

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