Answer:
280
Step-by-step explanation:
10x7 = 70
70/2 = 35
35x8 =280
the height is 70
L.H.S=(1-cosB)(1+cosB)
=(1-cos^2B). {using (a+b) (a-b)=(a^2-b^2)in second step}
=sin^2B
=1/cosec^2B
Therefore,L.H.S=R.H.S proved
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