if 7 Cos A = 8 find 15 cosec A - 8 sec B
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Answer:7×under root 15 -7
Step-by-step explanation:
Given, 7 cos A =8
cos A = 8/7
sec A = 7/8
cosA×cosA + sinA×sinA = 1
8/7×8/7 + sin A× sin A =1
Sin A ×sin A= 1-64/49
= 49-64/49
=15/49
sin A = under root 15 / 7
cosec A = 7 / under root 15
15 cosec A - 8 sec A
= 15 cosec A - 8 × 7/8
= 15 cosec A - 7
=15 × 7 /under root 15-7
= 7×Under root 15 - 7
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