# Proving Trigonometric Identities for sec, tan, cos and sin

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Prove

sec 2A + tan 2A = (cos A + sin A)/ (cos A - sin A)

Express this as a sum of 2 trigo functions

2(siny)(sin5y)

Prove

(sin2A)^2 - (sinA)^2 = (sinA)(sin3A)

https://brainmass.com/math/trigonometry/proving-trigonometric-identities-sec-tan-cos-sin-43685

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Prove

1) sec 2A + tan 2A = (cos A + sin A)/ (cos A - sin A)

2) Express this as a sum of 2 trigo functions= 2(siny)(sin5y)

3)Prove (sin2A)^2 - (sinA)^2 = (sinA)(sin3A)

Solution:

1) Taking the left hand side first we get,

LHS => sec2A + tan2A =

Taking LCD as 'cos2A', we get:

------- ïƒ (1)

Taking right hand side

and ...

#### Solution Summary

Trigonometric identities are proven. The solution is detailed and well presented.

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