If SecA * SinA equals 0, it implies that either SecA or SinA is equal to 0. Since SecA is the reciprocal of CosA, if SecA is 0, then CosA will be undefined. However, if SinA is 0, then CosA will be either 1 or -1 depending on the quadrant in which angle A lies.
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secA(sinA)=0
(1/cosA)(sinA)=0
tanA=0
Therefore A is in 1st or 3rd Quadrant
i.e A=0 Degrees, 180 Degrees....
This yields cosA=1 or cosA=-1
Use Cosine Rule a^(2) = b^(2) + c^(2) - 2bcCosA Algebrically rearrange CosA = [a^(2) - b^(2) - c^(2)] / -2bc Substitute CosA = [13^(2) - 12^(2) - 5^(2)# / -2(12)(5) CosA = [ 169 - 144 - 25] / -120 Cos)A) = [0] / -120 CosA = 0 A = 90 degrees (the right angle opposite the hypotenuse)/ However, If 'A' is the angle between '12' & '13' then 'a' is the side '5' Hence (Notice the rearrangement of the numerical values). CosA = [5^(2) - 12^(2) - 13^(2) ] / -2(12)(13) CosA = [ 25 - 144 -169] / -312 CosA = [ -288[/-312 CosA = 288/312 A = Cos^(-1) [288/312] A = 22.61986495.... degrees.
The value is 0.
Tan of 0 equals zero.
There aren't. There are three: Sine, Cosine and Tangent, for any given right-angled triangle. They are related of course: for any given angle A, sinA/cosA = tanA; sinA + cosA =1. As you can prove for yourself, the first by a little algebraic manipulation of the basic ratios for a right-angled triangle, the second by looking up the values for any value such that 0 < A < 90. And those three little division sums are the basis for a huge field of mathematics extending far beyond simple triangles into such fields as harmonic analysis, vectors, electricity & electronics, etc.
cotA*cotB*cotC = 1/[tanA+tanB+tanC]