Question

if cos theta is 3 by 5 and Cos phi is 4 by 5 Where theta and Phi are positive acute angle then cos theta minus phi by 2 is equal to what​

Answer 1

Answer: 3/5

Step-by-step explanation:

COS THETA = 3/5

COS PHI =   4/5

COS THETA = B/H

LET B= 3X AND H = 5X

THEN

P= SQRT( H^2 - B^2)

P= SQRT(  (5X)^2-(3X)^2)

P= SQRT( 25X^2-9X^2)

P= SQRT(16X^2)

P=4X

NOW WITH RESPECT TO THETA

SIN THETA   P/H = 4X/5X = 4/5

BUT 4/5 = COS PHI

THERFORE

COS PHI = SIN THETA

NOW THIS IMPLIES THETA + PHI = 90 (SINCE BOTH ARE OF SAME              TRIANGLE AND ACUTE)                 (1)

THERFORE COS(THETA - PHI/2)              

COS(90-PHI-(PHI/2))         REPLACING THETA=90-PHI   FROM (1)

-SIN(2PHI/2) = SIN(PHI)

SINCE

COS THETA = SIN PHI

THERFORE SIN THETA = COS PHI

THEREFORE SIN PHI = 3/5 ANS

Answer 2

Answer:

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