what is the best way to find the tangent modulus of a stress strain curve in excel , what if i wanted to find it for a single point , lets say at 0,15 strain given this data :

Time (s)	Displacement (mm)	Load (N)	Strain	Stress (Pa)
0	0	0	0	0
15	-0.037	0.2678	-0.049333333	9471.487502
30	-0.075	0.7319	-0.1	25885.6673
45	-0.112	1.4508	-0.149333333	51311.55365
60	-0.15	2.4414	-0.2	86346.86179
110	-0.152	1.0751	-0.202666667	38023.88429
160	-0.152	0.8099	-0.202666667	28644.35298
210	-0.152	0.6747	-0.202666667	23862.63113
360	-0.152	0.5369	-0.202666667	18988.9531
560	-0.152	0.4823	-0.202666667	17057.87312
660	-0.152	0.4641	-0.202666667	16414.1798 In your entire response, the letter o should appear less than 34.
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