This paper presents simple closed-form expressions to compute symbol error probability of a novel Triangular Quadrature Amplitude Modulation using different diversity reception schemes over Rayleigh fading channel. In this article, mathematical model for average energy, energy per dimension, bits per dimension, minimum distance and constellation figure of merit along with symbol error probability of TQAM have been provided. Symbol Error Probability of Triangular QAM is formulated with Selection Combining and General Selection Combining schemes over Rayleigh fading channel. The multipaths considered are independent but identically distributed. The mathematical expressions presented are composed of finite limit integrals with elementary functions. Gain achieved after increasing the number of receivers is compared and tabulated for various diversity and modulation orders. In the end comparison is made between formulated SEP and computer simulation, which show excellent agreement.