Given: tangent A = negative StartRoot 15 EndRoot What is the value of Tangent (A minus StartFraction pi over 4 EndFraction)?

( √15 + 8)/7

Step-by-step explanation:

TanA = -√15

.we are to find tan(A-π/4).

In trigonometry

Tan(A-B) = TanA - TanB/1+ tanAtanB

Hence:

tan(A-π/4) = TanA - Tanπ/4/1+ tanAtanπ/4

Substitute tan A value into the formula

tan(A-π/4) = -√15-tanπ/4 / 1+(-√15)(tanπ/4

tan(A-π/4) = -√15-1/1-√15

Rationalize

-√15-1/1-√15 × 1+√15/1+√15

= -√15-√225-1-√15/(1-√225)

= -2√15-15-1/1-15

= -2√15 -16/(-14)

= -2(√15+8)/-14

= √15 + 8/7

Hence the required value is ( √15 + 8)/7

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step-by-step explanation: