Use tables to find the acute angle θ, if the value of cos θ is :

(i) 0.9848

(ii) 0.9574

(i) Let cos θ = 0.9848

From graph,

cos 10° = 0.9848

θ = 10°.

Hence, θ = 10°.

(ii) Let cos θ = 0.9574

From graph,

cos 16° 48' = 0.9573

cos θ - cos 16° 48' = 0.9574 - 0.9573 = 0.0004

From table,

Difference of 1' = 0.0004 [To subtract]

∴ θ = 16° 48' - 1' = 16° 47'.

Hence, θ = 16° 47'.